RBSE Solutions for Class 12 Biology

RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion

August 6, 2019 by Prasanna Leave a Comment

Rajasthan Board RBSE Class 12 Biology Chapter 30 Man-Movement & Locomotion

RBSE Class 12 Biology Chapter 30 Multiple Choice Questions

Question 1.
The exoskeleton of animal is –
(a) Skull
(b) Ribs
(c) Nails
(d) Sternum
Answer:
(c) Nails

Question 2.
Matrix of a bone is of which protein –
(a) Chondrin
(b) Ossein
(c) Fibrin
(d) Retin in
Answer:
(b) Ossein

Question 3.
The function of the skeleton is –
(a) Protection of soft organs
(b) Provide space for muscle attachment
(c) Formation of blood corpuscles
(d) All of the above
Answer:
(d) All of the above

Question 4.
Reason of the pendular movement of cilia is –
(a) Sliding microtubules
(b) Contraction of microfibres
(c) Extension of cell wall
(d) Change in positions
Answer:
(b) Contraction of microfibres

Question 5.
According to sliding filament theory, the responsible molecule to decrease the length of muscle at the time of muscle contraction is –
(a) Collagen
(b) Actin
(c) Myosin
(d) Tyutin
Answer:
(b) Actin

Question 6.
Type of elbow joint is –
(a) Immovable joint
(b) Hinge joint
(c) Amphiarthrosis joint
(d) Pivot joint
Answer:
(b) Hinge joint

Question 7.
Contractile protein is –
(a) Troponin
(b) Myosin
(c) Tropomyosin
(d) All of the above
Answer:
(b) Myosin

Question 8.
Number of bones present in the posterior limbs of man –
(a) 14
(b) 24
(c) 26
(d) 30
Answer:
(d) 30

Question 9.
Storage of which substance in an anaerobic contraction of muscles become painful.
(a) Calcium ion
(b) Myosin
(c) Lactic acid
(d) Creatine phosphate
Answer:
(c) Lactic acid

Question 10.
Presence of which ions is essential for –
(a) Calcium
(b) Sodium
(c) Ferrous
(d) Potassium
Answer:
(a) Calcium

RBSE Class 12 Biology Chapter 30 Very Short Answer Type Questions

Question 1.
Write the structural and functional unit of muscle.
Answer:
Sarcomere.

Question 2.
By which structure muscle joint with a bone?
Answer:
Tendon.

Question 3.
By which process bone joints to bone?
Answer:
Ligament.

Question 4.
How many vertebrae from sacrum bone of man?
Answer:
Five Vertebrae.

Question 5.
How many bones participate in the formation of the skull of man?
Answer:
29 bones.

Question 6.
Give names of the main substances stored in the bones.
Answer:
Calcium phosphate, calcium carbonate, magnesium phosphate.

Question 7.
Which type of energy transfer occurs in muscular function?
Answer:
Chemical energy into mechanical energy.

RBSE Class 12 Biology Chapter 30 Short Answer Type Questions

Question 1.
What are cartilaginous bones? Explain.
Answer:
The bones are of 3 types:
1. Membranous or Investing bones –

They are formed by ossification in the membranes situated below the embryonic skin.
They invest soft cartilaginous parts of the skeleton & provide them strength.
Example: Flat bones of skull, clavicle, bones of digits etc.

2. Cartilaginous or Replacing bones –

It is formed in place of hyaline cartilage.
The matrix of the cartilage is destroyed by special osteoclasts.
Example: Bones of limbs, vertebral column, some bones of the skull.

3. Sesamoid bones –

It is formed by the ossification in the ligament.
Example: Patella’s bone.

Question 2.
Write the main functions of a Skeleton.
Answer:
Functions of the Skeleton:

The Skeleton forms a rigid framework and supports the body.
Skeleton provides a base for attachment of muscles.
Skeleton acts a lever during various movements of the body and also help in locomotion.
It protects a number of delicate organs such as brain, heart, lungs and spinal cord. 5. Blood corpuscles are produced in the red bone marrow

Question 3.

Write a note on the sternum.
Answer:
Sternum or Breast Bone:

It forms a respiratory basket along with ribs & thoracic vertebrae.
It is a flat bone which has distinct flat anterior & posterior sides.
It has 3 parts –
- Manubrium – Upper part, the clavicle & ribs are attached to it.
- Sternum body or Glandiolous – Middle part, 2nd, 3rd, 4th 5th, 6th & 7th ribs get attached to it.
- Xiphoid process or Ensiform – Posterior part, small & triangular plate.
The ribs articulate its ends.

Question 4.
Draw a neat and labelled diagram of the pelvic girdle.
Answer:
RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion img 3

Question 5.
Differentiate between ligament and cartilage.
Answer:

Ligament	Tendon
It connects bone to bone	It connects muscle to bone
Presence of Elastin protein	Presence of collagen Protein
Made up of yellow	Made up of white fibrous tissue collagen fibres

Question 6.
How muscle gets excited about contraction?
Answer:
Excitation for Muscle Contraction:

Nerve impulse promotes releasing of Neurotransmillar Acetylcholine the ends of the axon at Neuromuscular junction.
This chemical changes permeability in the plasma membrane of muscle towards Na⁺.
Due to this, Na⁺ enters into the muscle cell and causes a change in charge (axon potential), which is +ve inside the plasma membrane.
In normal condition, there is -ve charge inside the inner surface of the plasma membrane.
This positive change is transferred on the whole plasma membrane of muscle and generates an action potential, which is known as Excitation state of muscles.

Question 7.
If all joints of an arm of man become non-movable than what happens?
Answer:
Limb movement & Locomotion will become impossible.

Question 8.
What is osteoporosis?
Answer:
Osteoporosis:
Main characteristics of the disease are the loss of bone mass means deficiency of organic part (matrix) and minerals (calcium) in the bones. The bone becomes thin, weak and loses elasticity and strength. Chances of bone fracture are increased and slight jark or impact may lead to bone fracture.

It affects the whole body skeleton but pelvic, wrist, vertebrae etc are most adversely affected parts. It increases with the age but deficiency of estrogen also caused osteoporosis in old women. It may also be caused by hormones like calcitonin, PTH and glucocorticoids.

Question 9.
What is the source of energy for muscle contraction?
Answer:
Energy Sources for Contraction:

Both muscle contraction & relaxation require energy and the main source of energy is ATP. The muscles have less number of stored ATP. Hence, during contraction ATP is obtained from other sources.
The creatine – phosphate found in the muscles provides energy instantly because it has one high energy bond. It is also called as phosphagen. This process is catalysed by an enzyme creatine kinase.
The energy required in muscle contraction is obtained by oxidation of glucose but due to deficiency of O₂, this source fails to provide energy for a long period. Hence, the fermentation of the glycogen is the long-lasting source of the energy for muscle contraction.
Glycogen fermentation results in the formation of lactic acid. This lactic acid is transported into the liver by the blood. In the liver, 80% lactic acid is recovered into the glycogen (Glyconeogenesis) and the remaining 20% lactic acid is oxidized into CO₂ & H₂ in which energy is released. This energy is used in the glyconeogenesis.

Question 10.
If nerve going to skeletal muscle is cut, what will be an effect on contraction?
Answer:
There will be no contraction.

RBSE Class 12 Biology Chapter 30 Essay Type Questions

Question 1.
Write the structure of skeletal muscle in detail.
Answer:
Structure Of Skeletal Muscle:

Each skeletal muscle is spindle-shaped & has 2 distinct ends viz., Origin & Insertion. The origin & insertion remain attached to the bones with the help of tendon (cord-like structure) or aponeuroses (membrane-like structure).
The skeletal muscles of the tongue & upper part of the oesophagus are not attached to the skeleton. These muscles are also called as fatigued muscles or phasic muscles or striated muscles or somatic muscles.
Their structural unit is called as muscle fibre.
The muscle fibre is multinucleated or syncytial & bounded by sarcolemma. The muscle fibres are found in group & each group is called as fasciculus. The fasciculus is bounded by endomysium.
The fasciculi are also found in the group and each group of fasciculi is bounded by perimysium which is made up of connective tissues.
The whole skeletal muscle is bounded by an epimysium.

Fine structure of muscle Fibre:

The maximum length of the muscle fibre is 30 cm (1 – 30 cm) and the diameter is 0.01 to 0.1 mm. It is bounded by a sarcolemma or plasmalemma or myolemma. Its Sarcoplasm has many mitochondria which are called as acrosomes. The ER found in the sarcoplasm is called as Sarcotubules.
The sarcoplasm has three soluble proteins viz., myogenin, myoglobin & my albumin.
The sarcoplasm stores glycogen. In addition, it has less quantity of Na, Ca, P& Mg & more quantity of K.
The muscle fibre has many myofibrils. The length of the myofibril is similar to the muscle fibre but its diameter is 1 to 3µ.
The Myofibril has alternate A – bands (Anisotropic) & I – bands (Isotropic).
There is a Z – line (zigzag) in the middle of the I – band which is also called as Krau’s membrane.
The middle zone of the A-band is called an H – zone which has a central M – line.
The distance between two Z – lines is called sarcomere which is a functional unit of the muscle.
Each sarcomere includes one complete A – band and 2 halves l – bands on both the sides (12 + A + I/2).
The A – band is made up of mainly myosin filaments. The length of the myosin filament is 1.5µ & the diameter is 100Å.
The l-band is made up of mainly actin filaments. The length of the actin filament is 2µ & the diameter 50Å.
0.2µ of both the ends of the actin filaments size remain in the A – bands.
During the resting phase, the length of the A-band is 1.5µ & of the half I-band is 0.8µ. Hence, the length of the sarcomere is 3.1µ.
In the transverse section of the myofibril, through the end of A-band, has 5000 filaments (Both actin & myosin).
Each myosin filament is surrounded by 6 actin filaments (Hexagon). Similarly, one actin filament is surrounded by 3 myosin filaments (Trigon) The myosin filaments are provided with cross-links or bridges.
The cross-links remain directed towards the actin. They are attached at an angle of 60° & are equally spaced by 60 – 70 Å. The H – zone is without cross-links.

Question 2.
What is the joint? Describe various kinds of joints found in man.
Answer:
Joint:

In the vertebrates, joints are the places where two bones articulate with each other or bone and cartilage articulate with each other. In other words, the contact place between two or more bones or between bone and cartilage is known as Joint.
These joints facilitate movements of the body parts.

On the basis of movements, the Joints are of three types –
Synarthrosis or fixed or Immovable Joints:

The articulating bones are held together by a dense bundle of tough and white fibrous connective tissue which cannot be stretched or extended.
No movement is possible and hence called as fixed joints or synarthrosis.
Examples: Joints between the bones of the skull which are called Sutures.

Amphiarthrosis or partially movable joints:

It is a tough joint in which bones are joined by a disc of white fibrous cartilage which can be stretched a little.
Limited movement is possible.
Example: Pubic Symphoisis
It is of two types –
1. Pivot Joint – Joints between Atlas and axis vertebrae. It provides lateral movement.
2. Gliding Joint – In such joint, end of one bone glides over a certain portion of another bone. Movement in different directions is found. Joints between tarsal bones of the ankle, carpal bones in the wrist and in between sternum and clavicle.

Synovial or Diarthrosis ou movable Joints:

The Bones joined by synovial joints can move in one or more directions freely. A highly smooth thin layer of hyaline cartilage is found on the surface of the bone where joint occurs.
This cartilage minimizes the friction between the bones. Space is found between the joints of bones, which is called the synovial cavity. Bones are joined with each other by many ligaments. Ligaments fuse together and form a capsule which is covered by synovial membrane.
It secretes mucin containing synovial fluid. This fluid provides nutrition to hyaline cartilage and lubrication to joints.
It is of three types –
1. Ball and Socket Joint – It this joint ball-like the end of one bone fits into the socket of another bone. Movement of bone with the ball head in various planes is possible. Example: Shoulder Joint and Hip Joint.
2. Hinge joint – Resemble the hinges of doors. Movement in one direction only. Examples – Elbow joint, knee joint and finger joint, occipital condyle and atlas joint.
3. Ellipsoidal joint – Movement of one bone over another bone, allowing movements in around two axes. Joints between metacarpals and phalanges in hand, and metatarsals and phalanges in the foot. Another example is the joint between radius and carpals.

RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion img 6

Question 3.
Describe the mechanism of muscle contraction with diagrams.
Answer:
Mechanism of Muscle Contraction:
Sliding Filament Theory:

The process of muscle contraction can be explained with the help of “Sliding filament theory” which was given by A.F. Huxley, J. Hensen & H.E. Huxley.
According to it, the myosin filaments remain stationary & the actin filaments slide over the myosin with the help of cross-links.
During contraction, the length of the A – band remains unchanged but the length of the I – band & H – zone get reduced.
In H – zone, the actin filaments slide over each other.
The contraction results in the shortening of the sarcomere.
The relaxation of the muscle involves reverse sliding of the actin filaments to obtain an original position.

RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion img 7
Physiology of Muscle Contraction:
The process of muscle contraction & Relaxation involves four phases.
1. Excitation:

Nerve impulse promotes releasing of Neurotransmillar Acetylcholine the ends of the axon at Neuromuscular junction.
This chemical changes permeability in the plasma membrane of muscle towards Na⁺. Due to this, Na⁺ enters into the muscle cell and causes a change in charge (axon potential), which is +ve inside the plasma membrane. In normal condition, there is -ve charge inside the inner surface of the plasma membrane.
This positive change is transferred on the whole plasma membrane of muscle and generates an action potential, which is known as Excitation state of muscles.

2. Excitation – Contraction Coupling:

This is the process in which action potential promotes contraction in a muscle cell. This action potential instantly transfers to the T – system.
Due to this potential, Ca⁺⁺ released from the sarcoplasmic reticulum and join with troponin C.
It results in configurational changes in Troponin atoms.
As a result, tropomyosin and troponin, both are released from the active site of actin.
As soon as active site is made free the myosin filament joins with actin and contraction process starts.

3. Contraction:

Contraction occurs by sliding filament process, which is initiated by joining of actin & myosin transverse bridge.
Just before joining of active filament at the active site, one atom of ATP joins at the head of the transverse bridge. ATP present in myosin head breaks down into ADP+ Pi by ATPase.
ADP⁺ Pi remain attached or joined with the head after that myosin head joins with the active site of the actin filament.
There are conformational changes in the head due to joining of head and active site. Due to this, there is bending in the head (just as we bend our finger) and actin filament is pulled towards the centre of the sarcomere (H zone) and energy is obtained to do this by breaking down of ATP.
Due to bending of head, ADP+ Pi are also released and as they are released, instantly new ATP joins with the head.
Due to joining of the head with ATP, it separates from actin. Again ATP is broken down Myosin head now joins again at the new active site and this process is repeated.
Due to repeated acts of the head of the transverse bridge, active filament slides and leads to contraction. In contraction many filaments. Cross bridges (transverse bridges) participate. The contraction in muscle tissue (filament) continues till Ca⁺⁺ remain attached with troponin.

RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion img 8
4. Relaxation:

When contraction through nerve impulse is stoped in muscle then Ca⁺⁺ is sent back to muscle sarcoplasmic reticulum, which results in troponin – C free from Ca⁺⁺ and active sites of actin filament are blocked.
Now there is no joining or bonding of actin and myosin filament. Filaments come into their original position and muscles relax.

Question 4.
Write the structure of girdles and their significance.
Answer:
Pectoral Girdle:

It supports fore limbs & protects chest organs.
It has two equal halves.
Each half has a clavicle & a scapula-coracoid bones.
The clavicle is a rod-like bone which is also called as collar bone.
The scapula is a broad & flat bone which is found in all mammals.
The coracoid is get fused with the scapula & found in the form of a coracoid process.
The supra scapula is absent in the pectoral girdle of Man.
The dorsal side of the scapula has a spine. The anterior & ventral extension of the spine is called an acromial process.
The posterior process of acromial in the rabbit is called the acromion process.
The head of the scapula-coracoid has a cavity, the glenoid cavity.
The head of the humerus bone articulates to the glenoid cavity.

RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion img 9

Pelvic Girdle:

It supports hind limbs.
It has 2 equal halves & each half is called as os-innominate.
Both the os-innominate remain united by pubic symphysis which is made up of fibrous cartilage.
The pelvic girdle of the rabbit is W – shaped.
Each os – innominate of the rabbit has 4 bones – Ilium, Ischium, Pubic & Cotyloid.
Each os – innominate has a groove, the acetabulum. The head of the femur articulates with it.
In the rabbit, the pubic bone does not participate in the formation of the acetabulum. There is a small cotyloid bone between the acetabulum & the pubic.
In man, cotyloid bone is absent. Hence, each os-innominate has 3 bones – Ileum, Ischium & Pubic. All of them participate in the formation of the acetabulum.
There is an obturator foramen between pubic & ischium bones.

RBSE Solutions for Class 12 Biology Chapter 30 Man-Movement & Locomotion img 10

RBSE Solutions for Class 12 Biology

RBSE Solutions for Class 12 Biology Chapter 23 Man-Respiratory System

August 5, 2019 by Prasanna Leave a Comment

Rajasthan Board RBSE Class 12 Biology Chapter 23 Man-Respiratory System

RBSE Class 12 Biology Chapter 23 Multiple Choice Questions

Question 1.
Energy used in respiration is –
(a) Physical energy
(b) Chemical energy
(c) Kinetic energy
(d) Electric energy
Answer:
(b) Chemical energy

Question 2.
During inhalation, the diaphragm is –
(a) Oblique
(b) Dome-shaped
(c) Normal
(d) Flattened
Answer:
(d) Flattened

Question 3.
During inspiration occurs –
(a) Contraction of diaphragm and external intercostal muscles.
(b) Relaxation of diaphragm and external intercostal muscles.
(c) Contraction of the only diaphragm.
(d) Relaxation of only external intercostal muscles
Answer:
(a) Contraction of diaphragm and external intercostal muscles.

Question 4.
During expiration occurs –
(a) Contraction of diaphragm and external intercostal muscles.
(b) Relaxation of diaphragm and external intercostal muscles.
(c) Relaxation of the diaphragm only.
(d) Contraction of diaphragm and external intercostal muscles.
Answer:
(b) Relaxation of diaphragm and external intercostal muscles.

Question 5.
Rate of respiration found in the resting stage of an adult is –
(a) 20 – 22 per minute
(b) 18 – 20 per minute
(c) 16 – 20 per minute
(d) 14 – 16 per minute
Answer:
(c) 16 – 20 per minute

Question 6.
Tidal Volume found in a normal man during resting phase –
(a) 1.2 litre
(b) 2.5 litre
(c) 0.5 litre
(d) 4.5 litre
Answer:
(c) 0.5 litre

Question 7.
The end part of trachea in the lung is –
(a) Bronchioles
(b) Alveoli
(c) Bronchi
(d) Air sac
Answer:
(b) Alveoli

Question 8.
Whizzing sound during expiration is signal of the disease –
(a) Emphysema
(b) Asthma
(c) Bronchitis
(d) Silicosis
Answer:
(b) Asthma

Question 9.
Labour working in the mines and factories are possible to suffer more from the diseases.
(a) Pneumonia
(b) Bronchitis
(c) Emphysema
(d) Silicosis
Answer:
(d) Silicosis

Question 10.
The total capacity of lungs is –
(a) 4600 ml
(b) 3500 ml
(c) 5800 ml
(d) 2300 ml
Answer:
(c) 5800 ml

RBSE Class 12 Biology Chapter 23 Very Short Answer Questions

Question 1.
What is external expiration?
Answer:
Giving out of the air (CO₂) from the lungs into the environment is called as external respiration.

Question 2.
What is the respiratory surface?
Answer:
The surface which participates in the exchange of O₂ and CO₂ is called as respiratory surface.
Example: Lung alveoli.

Question 3.
Where diaphragm is found?
Answer:
It is situated between the thoracic and abdominal.

Question 4.
Write the names of inspiratory muscles.
Answer:
External and Internal intercostal muscles.

Question 5.
Write the names of two diseases caused by smoking?
Answer:
Asthma and Emphysema.

Question 6.
What is expiratory reserve volume?
Answer:
The amount of air expired over and above the normal expiration. It is from 1000 to 1100 ml.

Question 7.
What is inspiratory reserve volume?
Answer:
The amount of air inspired over and above the normal inspiration. It is from 2500 to 3000 ml.

Question 8.
What is residual volume?
Answer:
The amount of air left in the lungs after forced expiration. It is 1100 – 1200 ml.

Question 9.
What is inspiratory capacity?
Answer:
It includes tidal volume and Inspiratory reserve volume. It is 3500 ml.

Question 10.
What is a functional residual capacity?
Answer:
The amount of air left in the lungs after a normal expiration. It is 2300 ml.

Question 11.
What is the significance of artificial respiration?
Answer:
It is used to save the life of any person subjected to an accident such as gaseous toxicity, electric shock, CO, toxicity etc. The best method is mouth to mouth breathing.

RBSE Class 12 Biology Chapter 23 Short Answer Questions

Question 1.
Explain the process of inspiration.
Answer:
Inspiration:

The entry of air into the lungs is called as inspiration or inhalation.
It involves:
- Contraction of the diaphragm muscles. As a result, it moves downwards i.e. the diaphragm becomes flat.
- Contraction of external intercostal muscles & relaxation of internal intercostal muscles. As a result, the ribs move outward & forward i.e. anteroventral movement of the ribs. The above changes in the factors cause an increase in the thoracic volume but the thoracic pressure is reduced. Hence, due to less pressure air enters into the lungs.

Question 2.
Explain the process of expiration.
Answer:
Expiration:

The exit of air (CO₂) from the lungs is called expiration or exhalation.
It involves:
- Relaxation of the muscles of the diaphragm, As a result, the diaphragm moves upwards & resumes dome shape.
- Contraction of internal intercostal muscles and relaxation of external intercostal muscles. As a result, the ribs move inward & backwards i.e. posterior – the dorsal movement of the ribs.
  The above changes in the factors cause a decrease in the thoracic volume but the thoracic pressure is increased. Hence, due to increased pressure air comes out of the lungs.

Note: The breathing rate in adult human beings is 12 to 20 per minute.
RBSE Solutions for Class 12 Biology Chapter 23 Man-Respiratory System 1

Question 3.
Explain the process of artificial respiration.
Answer:
Artificial Respiration:

During accidental conditions of any person such as gaseous toxicity or CO effect, electric shock etc, if breathing stops and heartbeats continue then human life can be saved by giving artificial respiration.
Normally, the artificial respiration activates the respiratory centres, hence normal breathing can be restored.
Many methods of artificial respiration are known but “Mouth to Mouth technique” is most effective.
Following are the main steps for artificial respiration:
- Keep the patient on a hard bed in a straight position. Keep one hand on the head of the patient and another hand below the head, so respiratory passage gets open.
- Close the nose of the patient with the hand which is on the head of the patient and put a mouth on the patient’s mouth in such a way that airtight position forms. The hand below the head is to be remained as such so that neck remains stretched.
- Push air into the mouth of the patient forcefully about 12 times of tidal volume (500 ml).
- Open the nose and mouth of the patient and allow expiration.

Question 4.
What is Emphysema disease? How it can be prevented?
Answer:
Emphysema:

It is caused due to heavy smoking and air pollution.
Smoking causes continuous stimulation in the lungs which destroys the alveolar walls.
This results in increased air space but decreases in the respiratory surface in the lungs.
Lung elasticity is also reduced due to the increased amount of connective tissues. It causes difficulty in expiration.
Avoiding smoking, use of antibiotics and bronchial-dilators are helpful to get relief.

Question 5.
What is respiration? Define external and internal respiration.
Answer:
Respiration:

The body needs energy to perform various vital activities.
This energy is obtained mainly by oxidation of carbohydrates & fats. Oxidation of these substances consumes O₂ & release CO₂. The process of consumption of O₂ and the release of CO₂ is termed as respiratory exchange.
According to Carter, respiration involves external respiration, internal respiration & cellular respiration.
Mammals exhibit aerial respiration which needs a respiratory system.
The respiratory system concerns with an intake of O₂ and giving out of CO₂.

Types of Respiration:
The respiration is of two types:

External respiration: It takes place in the lung alveoli. taking in of O₂ and giving out of CO₂ is termed as external respiration or Breathing or Ventilation. It is a physical process.
Internal respiration: In taking of O₂ by the body cells and production of CO₂ and ATP is called internal or cellular respiration.

The internal respiration is of two types:

Aerobic respiration: Cellular respiration in the presence of O₂ is called aerobic respiration.
Anaerobic respiration: The cellular respiration in lack of O₂ is called anaerobic respiration.

RBSE Class 12 Biology Chapter 23 Essay Questions

Question 1.
Describe the human respiratory system.
Answer:
Respiratory Organs of Human beings:
The respiratory passage includes the following organs –

Nostrils:

There is a pair of external nares which are situated obliquely at the tip of the snout. This condition is called as diaphanous.
Their cavities are called as fossae or nasal passage. Both the fossae remain separated by a nasal septum which is made up of mesethmoid cartilage.

Nasal Cavities:

The external nares open into nasal cavities which are situated dorsally to the palate. The nasal cavities open into the nasopharynx through a pair of internal nares or choanae.
Nasal cavities are formed as an invagination of the skin and it contains a turbinal bone which is a scrolled & porous bone,
The projections of the turbinal bones are called as conchae.
The nasal cavities remain lined by pseudo-stratified epithelium which is ciliated & glandular.
There are Bowmann’s glands to secrete the mucus.
The nasal epithelium is electroreceptors and it is also called as Schneiderian epithelium.
Functions of nasal cavities –
- It filters the inspired air
- It acts as electroreceptor
- According to new researches, it is provided with pheromones receptors.
- It maintains the temperature of inspired air by cooling’warming the air.
- It makes the inspired air moist.

Pharynx:

Its a dorsal part is called as nasopharynx & ventral part as oro-pharynx.
Posteriorly, it has two openings viz.-gullet (dorsal) & glottis (ventral). The gullet leads into an oesophagus & the glottis opens into a larynx.
The glottis remains covered by a cartilaginous flap which is called as epiglottis. The epiglottis prevents the entry of food & water into the larynx.

Larynx:

It is located in the anterior end of the throat which is formed by the modification of the anterior end of the trachea.
It is also called a sound-producing organ.
Formation of larynx involves 4 cartilages which are of 3 types viz.,
- Thyroid-one largest, C-shaped & forms ventrolateral sides.
- Cricoid-one, ring-like, broad dorsally & forms base of the larynx.
- Arytenoid-Two small & from the dorsal side.
The anterior end of the arytenoid cartilage is knob-like and it is called as the cartilage of Santorini.
The larynx has two pairs of elastic vocal cords which remain stretched between the thyroid and arytenoid cartilages:
- Anterior or False vocal cords
- Inelastic & pinkish in colour.
- Posterior or True vocal cords.

RBSE Solutions for Class 12 Biology Chapter 23 Man-Respiratory System 2

Trachea or Windpipe:

It is a simple tube which is elastic & semi-transparent.
Its length in man is of 10 cm.
It is located in the neck ventral to the oesophagus.
It is lined by pseudostratified epithelium & ciliated internally. These cilia beat constantly to force out the mucous.
The trachea is supported by tracheal rings made up of hyaline cartilage. These rings are C-shaped i.e. incomplete dorsally to facilitate oesophageal movements.
The posterior end of trachea bifurcates to form two bronchi. These bronchi are also thin-walled & elastic but they are supported by complete cartilaginous rings. Each bronchus enters into its respective lung.

Lungs:

Man has a pair of lungs which are situated in the thoracic cavity on both the sides of the heart.
The lungs are elastic, spongy, light pink, unequal & without muscles.
In the human being, the left lung consists of two lobes viz., left superior lobe & left inferior lobe. Whereas, the right lung includes three lobes viz.-superior lobe, middle lobe & inferior lobe.
Each lung is bounded by two pleural membranes viz.,
- External or Parietal pleuron.
- Internal or Visceral pleuron.
Both the pleura remain closely applied to each other.
The space between the lung and the pleura is called a pleural cavity.
Each bronchus enters into the lung of own side & divide to form secondary or lobular bronchi (4 secondary bronchi in right lung & 2 secondary bronchi in the left lung).
Each secondary bronchus divides to form tertiary or segmental bronchi, which further divide to form intrapulmonary bronchi. The ends of intrapulmonary bronchi divide to form terminal bronchioles which further form respiratory bronchioles.
These bronchioles lack cartilaginous rings. Each respiratory bronchiole gives out 2 to 11 alveolar ducts. Each alveolar duct gives out small ducts, the atria. Each atrium forms small bag-like alveoli or air sacs which are made up of squamous epithelium.
Internally, the alveolus is lined by mucous & there is a network of blood capillaries outside. The alveoli provide more surface for the exchange of gases.
The diameter of a lung alveolus is 0.2 mm.

Question 2.
Explain the process of respiration and its role.
Answer:
Respiration process involves two steps:

Inspiration
Expiration

1. Inspiration:

The entry of air into the lungs is called as inspiration or inhalation.
It involves:
- Contraction of the diaphragm muscles. As a result, it moves downwards i.e. the diaphragm becomes flat.
- Contraction of external intercostal muscles & relaxation of internal intercostal muscles. As a result, the ribs move outward & forward i.e. anteroventral movement of the ribs.
  The above changes in the factors cause an increase in the thoracic volume but the thoracic pressure is reduced. Hence, due to less pressure air enters into the lungs.

2. Expiration:

The exit of air (CO₂) from the lungs is called expiration or exhalation.
It involves:
- Relaxation of the muscles of the diaphragm, As a result, the diaphragm moves upwards & resumes dome shape.
- Contraction of internal intercostal muscles and relaxation of external intercostal muscles. As a result, the ribs move inward & backwards i.e. posterior – the dorsal movement of the ribs.
  The above changes in the factors cause a decrease in the thoracic volume but the thoracic pressure is increased. Hence, due to increased pressure air comes out of the lungs.

Note: The breathing rate in adult human beings is 12 to 20 per minute.
RBSE Solutions for Class 12 Biology Chapter 23 Man-Respiratory System 4
Question 3.
Write short notes on:

Artificial respiration
Respiratory diseases
Respiratory volumes

Answer:
1. Artificial Respiration:

During accidental conditions of any person such as gaseous toxicity or CO effect, electric shock etc, if breathing stops and heartbeats continue then human life can be saved by giving artificial respiration.
Normally, the artificial respiration activates the respiratory centres, hence normal breathing can be restored.
Many methods of artificial respiration are known but “Mouth to Mouth technique” is most effective.
Following are the main steps for artificial respiration:
- Keep the patient on a hard bed in a straight position. Keep one hand on the head of the patient and another hand below the head, so respiratory passage gets open.
- Close the nose of the patient with the hand which is on the head of the patient and put a mouth on the patient’s mouth in such a way that airtight position forms. The hand below the head is to be remained as such so that neck remains stretched.
- Push air into the mouth of the patient forcefully about 12 times of tidal volume (500 ml).
- Open the nose and mouth of the patient and allow expiration.

2. Respiratory disorders:
Asthma:

It is a respiratory disease. It is a condition in which a person’s air passage becomes inflamed, narrow, swells and produces more mucus, which makes difficult to breathe.
The disease is caused due to pollens, dust particles, cold or smoking etc. It causes difficulty in breathing, chest pain, coughing and wheezing. The best remedy to prevent asthma is to live away from allergens.
Asthma can be managed with rescue inhalers to treat symptoms i.e. bronchodilators. Antibiotics are required to cure it.

Bronchitis:

This disease involves inflammation of the timing of bronchial tubes which carry air to and fro from the lungs.
Symptoms include – swelling on the internal lining of bronchitis that causes constant coughing. Bronchitis may be acute or chronic.
It may also be due to chemicals in the smoke of tobacco. Avoiding smoking is the best way to prevent asthma.

Emphysema:

It is caused due to heavy smoking and air pollution.
Smoking causes continuous stimulation in the lungs which destroys the alveolar walls.
This results in increased air space but decreases in the respiratory surface in the lungs.
Lung elasticity is also reduced due to the increased amount of connective tissues. It causes difficulty in expiration.
Avoiding smoking, use of antibiotics and bronchial-dilators are helpful to get relief.

Pneumonia:

It is an infectious disease which is caused by the infection of streptococcus pneumonia bacteria.
The lung alveoli get filled with dead cells (WBC) and fluid because of infection.
The patient faces breathing problems.
It is more common during childhood and old age.
Antibiotics and bronchodilators are beneficial in curing.

Cancer of Lung:

Its main cause is smoking.
The chemicals present in the smoke of cigarettes are carcinogens.
The smoke may cause irregular cell divisions in bronchioles and slowly cause being cancer.

Silicosis and Asbestosis:

These diseases are due to air pollution.
Mainly, they occur in persons who are working at mines and factories of silica and asbestos.
The particles of silica or asbestos enter into the lungs and cause fibrosis in the upper part of the lungs.
These diseases are not curable, hence prevention is better.

3. Respiratory volumes:

Tidal Volume (TV) – The amount of air expired/inspired during one breath is termed as tidal volume. It is 500 ml in human beings.
Inspiratory Reserve Volume (IRV] – The amount of air inspired over and above the normal inspiration. It is 2500 to 3000 ml in human beings.
Expiratory Reserve Volume [ERV] – The amount of air expired over and above the normal expiration. It is 1000 to 1100 ml in human beings.
Residual air (RV) – It is the amount of air left in both the lungs after forced expiration. It is about 1100 to 1500 ml in human beings.
Inspiratory Capacity (IC) – The maximum inspired air is called as IC. It includes tidal volume and IRV. It is about 3500 ml in human beings.
Expiratory Capacity (EC) – The maximum expired air is called as EC. It includes TV + ERV. It is about 1500 to 1600 ml. in human beings.
Functional Residual Capacity (FRC) – The amount of air left in the lungs after a normal expiration. It includes RV + ERV. It is about 2300 ml in human beings.
Vital Capacity (VC) – The amount of air expired maximum from both the lungs. It is IRV + TV + ERV. In human beings, it is 4600 ml.
Total Lung Capacity (TLC) – The total amount of air in both the lungs is called TLC. It is VC + RV. It is 5800 ml in human beings.

RBSE Solutions for Class 12 Biology

RBSE Solutions for Class 12 Biology Chapter 33 Embryonic Development in Man

August 5, 2019 by Prasanna Leave a Comment

Rajasthan Board RBSE Class 12 Biology Chapter 33 Embryonic Development in Man

RBSE Class 12 Biology Chapter 33 Multiple Choice Questions

Question 1.
How many cells are found in Morula?
(a) 4
(b) 8
(c) 16
(d) 32
Answer:
(c) 16

Question 2.
Which cavity is formed during gastrulation?
(a) Animal pole
(b) Vegetal pole
(c) Blastocoel
(d) Amniotic cavity
Answer:
(c) Blastocoel

Question 3.
Major parts of eyes are derived from which germinal layer?
(a) Ectoderm
(b) Mesoderm
(c) Endoderm
(d) None of the above
Answer:
(a) Ectoderm

Question 4.
Formation of Kidney takes place from which of the following germinal layer.
(a) Ectoderm
(b) Mesoderm
(c) Endoderm
(d) None of the above
Answer:
(b) Mesoderm

Question 5.
Which activity does not takes place during the first week of embryonic development of human?
(a) Implantation
(b) Formation of blastocoel
(c) Morula formation
(d) Formation of Primitive streak
Answer:
(d) Formation of Primitive streak

Question 6.
Development of heart completes during embryonic development of human in –
(a) First week
(b) Second week
(c) 3rd to 6th week
(d) 7th to 8th week
Answer:
(d) 7th to 8th week

RBSE Class 12 Biology Chapter 33 Very Short Answer Type Questions

Question 1.
What is Embryogenesis?
Answer:
The process of formation of the multicellular zygote from the single-celled zygote is called embryogenesis.

Question 2.
What kind of cell divisions take place during cleavage?
Answer:
Mitosis division but it is without growth phase.

Question 3.
What are blastomeres?
Answer:
The cells formed as a result of cleavage are called blastomeres.

Question 4.
How many blastomeres are found in morula?
Answer:
16 blastomeres.

Question 5.
What is derived from blastopore in a man?
Answer:
Anus.

RBSE Class 12 Biology Chapter 33 Short Answer Type Questions

Question 1.
How the formation of blastocyst takes place in Human?
Answer:
Blastulation:

Formation of blastula/blastocyst from morula is known as blastulation.
In human morula, the outer cuboidal cells become flattened when it reaches into the uterus.
These flattened cells are called as Trophoblast, by which they adhere with uterine epithelium.
Cleavage continued and a cluster of cells differentiates into two distinct groups, the epithelial-like trophoblast or nutritive cells surrounding the expanding cavity and inner cell mass of formative cells of the embryo.
The cavity is called blastocoel and embryo is known as a blastocyst (a kind of blastula) in human.

Question 2.
Differentiate between blastulation and gastrulation?
Answer:

Blastulation	Gastrulation
It results in the formation	It results in the formation of blastula of the gastrula
Formation of Blastocoel	Formation of Gastrocoel
No opening is formed	Blastopore is formed

RBSE Class 12 Biology Chapter 33 Essay Type Questions

Question 1.
How and when the formation of blastocyst takes place?
Answer:
Blastulation:

Formation of blastula/blastocyst from morula is known as blastulation.
In human morula, the outer cuboidal cells become flattened when it reaches into the uterus.
These flattened cells are called as Trophoblast, by which they adhere with uterine epithelium.
Cleavage continued and a cluster of cells differentiates into two distinct groups, the epithelial-like trophoblast or nutritive cells surrounding the expanding cavity and inner cell mass of formative cells of the embryo.
The cavity is called blastocoel and embryo is known as a blastocyst (a kind of blastula) in human.

Question 2.
Describe gastrulation in Man.
Answer:
Gastrulation:
During implantation, zona pellucida disappears and the trophoblast cells become giant-sized and aggressively invade the uterine tissue and make contact informing the placenta.

Inner cell mass at this time undergoes differentiation and a layer of very flat cells appear on the interior surface of the inner cell mass that forms future endoderm. The remaining dorsal inner cell mass is called epiblast, which is presumptive material for ectoderm and mesoderm.

Formation of three germinal layers from a single-layered blastocyst. The blastocoel gets obliterated & a new cavity called gastric or archenteron is formed. It is called a gastrula. The method by which blastula becomes or converted into gastrula is called Gastrulation.

The mesodermal cells soon involute through the primitive streak and diverge anteriorly and laterally, occupying a position between ectoderm and endoderm. Epiblast also contributes some cells to endoderm. The cells migrating to their future places by amoeboid movements.

Question 3.
A child born after seven months gestation period can survive. Explain How?
Answer:
Up to seven months of embryonic development, most of the vital body organs are formed and developed. This is the main region that embryo can survive.

RBSE Solutions for Class 12 Biology

RBSE Solutions for Class 12 Biology Chapter 22 Man-Digestive System

August 5, 2019 by Prasanna Leave a Comment

Rajasthan Board RBSE Class 12 Biology Chapter 22 Man-Digestive System

RBSE Class 12 Biology Chapter 22 Multiple Choice Questions

Question 1.
Which part secretes renin?
(a) Liver
(b) Colon
(c) Stomach
(d) Rectum
Answer:
(c) Stomach

Question 2.
Pancreatic juice is –
(a) Acidic
(b) Alkaline
(c) Neutral
(d) None of the above
Answer:
(b) Alkaline

Question 3.
Kupffer’s cells are found in –
(a) Pancreas
(b) Small intestine
(c) Large intestine
(d) Liver
Answer:
(d) Liver

Question 4.
Amylase enzyme acts on which substrate –
(a) Protein
(b) Carbohydrate
(c) Fatty acid
(d) Fat
Answer:
(b) Carbohydrate

Question 5.
Which converts inactive pepsinogen into active pepsin –
(a) Ptyalin
(b) HCL
(c) Bile
(d) Renin
Answer:
(b) HCL

Question 6.
How many salivary glands are found in a man?
(a) 5 pairs
(b) 2 pairs
(c) 4 pairs
(d) 3 pairs
Answer:
(d) 3 pairs

Question 7.
Lier cells synthesize –
(a) Bile juice
(b) Trypsin
(c) Amylopsin
(d) Lipase
Answer:
(a) Bile juice

Question 8.
Where the islet of Langerhans are found –
(a) Pancreas
(b) Ileum
(c) Colon
(d) Liver
Answer:
(a) Pancreas

Question 9.
Vitamin which helps in maturation of RBC –
(a) D
(b) A
(c) B
(d) B₁₂
Answer:
(d) B₁₂

Question 10.
The part of the alimentary canal which bears villi –
(a) Stomach
(b) ileum
(c) Oesophagus
(d) Rectum
Answer:
(b) ileum

RBSE Class 12 Biology Chapter 22 Very Short Answer Questions

Question 1.
Where Kupffer’s cells are found?
Answer:
Liver.

Question 2.
What role of vitamin K?
Answer:
It helps in blood clotting by forming prothrombin in the liver.

Question 3.
Which organ synthesizes and stores glycogen?
Answer:
Liver.

Question 4.
Deficiency of Vitamin D causes deficiency of which mineral in the body?
Answer:
Calcium.

Question 5.
Name the disease caused by protein deficiency.
Answer:
Kwashiorkor and Marasmus.

Question 6.
Where the digested fat is absorbed?
Answer:
Ileum.

Question 7.
Vitamin which can be synthesizes in the human body?
Answer:
Vitamin – D.

Question 8.
Write the dental formula of man.
Answer:
12/2, C 1/1, Pm 2/2, M 3/3 ⇒ 16 × 2 ⇒ 32.

Question 9.
What is bolus?
Answer:
The semisolid mass formed in the buccal cavity after salivary digestion is called bolus.

Question 10.
What are Brunner’s glands?
Answer:
They are multicellular glands which are found in the submucosa region of the duodenum. They secrete mucously.

Question 11.
What do you understand by Peyer’s patches?
Answer:
The patches of lymph glands found in the mucosa layer of the small intestine are called Peyer’s patches.

Question 12.
What is the sphincter of Odi?
Answer:
The common bile duct opens into the duodenum. It’s opening is regulated by a sphincter of Odi.

RBSE Class 12 Biology Chapter 22 Short Answer Questions

Question 1.
Write the functions of the liver.
Answer:
Functions of the Liver:

It forms bile juice. The bile juice is synthesized in the liver cells constantly & drops into the bile canaliculi.
The bile canaliculi unite to form cystic ducts which finally open into the gall bladder.
The liver stores vitamins A, D & B_12.
It synthesizes blood clotting factors.
During the embryonic stage, it acts as a haemopoietic organ.
It stores extra food in the form of glycogen.
It performs detoxification of many toxins.
It synthesizes many proteins like albumin, fibrinogen, globulin etc.
It synthesizes urea by ornithine cycle.
It is the site for glycogenesis, glycogenolysis, gluconeogenesis, deamination, lipogenesis etc.
It synthesizes heparin which is an anticoagulant.

Question 2.
What is emulsification? Write its importance.
Answer:
Fats are found in large globules which can’t be acted by enzyme lipase. The bile salts found in the bile juice coverts bigger fat globules into smaller globules of lu diameter. It is called emulsification. The emulsified fat can easily be acted by the enzyme lipase.

Question 3.
What are Chylomicrons?
Answer:
The cells of Mucosa of ileum absorb fatty acids and glycerol in the presence of bile salts. The cells synthesize triglycerides and pack them in small round packets which are called as chylomicrons (Diameter lµ to 3, 5µ). They are released into the lacteals by exocytosis.

Question 4.
What is Kwashiorkar disease? Write its symptoms.
Answer:
Kwasikorkar disease:
It is a deficiency disease which occurs in children up to 5 years due to a deficiency of proteins. Suc children consume less than 1 gm protein per kg. body weight per day.
Symptoms:

Loss of body weight and distaste to food.
Skin becomes scaly and black.
Oedema in the body due to water retention and building of belly.
Hair becomes scanty, thin and grey.

Question 5.
What is marasmus disease? Write its symptoms.
Answer:
Marasmus:
It is a deficiency disease which occurs in children up to one year due to deficiency of proteins, carbohydrates and fats.
Symptoms:

A sharp decrease in body weight (less than 60% of the standard bodyweight).
The body is reduced to a skeleton, wrinkled skin, Sunken eyes etc.
Thin limbs Ribs visible etc.

PEM can be corrected by consuming a protein-rich diet.

RBSE Class 12 Biology Chapter 22 Essay Type Questions

Question 1.
Describe the alimentary canal of man. Give a labelled diagram.
Answer:
Alimentary Canal:
1. The alimentary canal is a simple tube between the mouth & the anus which exhibits many modifications to perform different functions.

2. The alimentary canal originates from embryonic ectoderm & endoderm.
RBSE Solutions for Class 12 Biology Chapter 22 Man-Digestive System 1
3. Its length is about 9 meter.

1. Mouth and Buccal Cavity:

It is a transverse slit-like structure.
The mouth is guarded by a pair of lips viz. upper lip and lower lip. The lips of the mammals are muscular and movable.
The mouth opens into a buccal cavity.
It is a cavity in the head region. Its dorsal side is made up of palate, the ventral side is made up of throat while both the lateral sides are made up of cheeks.
The ventral side of the buccal cavity is occupied by a flat and muscular tongue.
The tongue bears taste buds which are sensory to sour, salty, sweet and bitter tastes.
Human tongue bears three types of taste buds. viz.,
1. Circumuallate
2. Fungiform
3. Filiform
Foliate taste buds are absent in human beings.
Functions of the tongue
1. It functions as gusto-receptor.
2. It helps in the mastication of the food.
3. It helps in the swallowing of the bolus.
4. It acts as a brush to clean the teeth.
5. In human beings, it helps in speech.
The buccal cavity has upper & lower jaws which are beset with teeth.
The arrangement of the teeth on the jaws is called dentition.

1.1. Salient Features of Teeth:

The mammalian teeth are thecodont.
The mammalian teeth are diphyodont i.e. there are two sets of the teeth in the life viz.,
1. Milk or Deciduous teeth – the There number is 20.
2. Permanent or Non-deciduous teeth – the There number is 32.
The mammalian teeth are heterodont i.e. 4 types of teeth are found viz.,
1. Incisors
2. Canines
3. Premolars
4. Molars
Last four molars are called wisdom teeth.
Dental formula:
1. The dental formula denotes position, number & type of teeth in the jaws.
2. The dental formula denotes teeth in half of the jaws.
3. The total number of teeth can be obtained by doubling the dental formula.
4. The dental formula of Man
  - Infant ⇒ 12/2, C 1/1, Pm 0/0, M2/2 ⇒ 10 × 2 ⇒ 20
  - Adult ⇒ 12/2, C 1/1, Pm 2/2, M 3/3 ⇒ 16 × 2 ⇒ 32

The tooth is ectomesodermal in origin and each tooth have three parts –
(1) Crown: It is the exposed part of the tooth which is chisel-shaped in the incisors, pointed in the canines and broad & flat in the cheek teeth.

(2) Neck: It is the middle part of the tooth which is covered by the gums.

(3) Root:

It remains embedded in the bony socket.
The number of the root in the incisors & canines is 1 – 1, in premolars is 2 and in molars is 3 – 5.
The root is bounded by a periodontal membrane.
The tooth is mainly made up of dentine. It is provided with canaliculi.
The crown part of the tooth is covered by a hard substance, the enamel which is formed by ectodermal ameloblasts.
It is the hardest substance in the body which consists of 95% inorganic substances (calcium phosphate, Mg, Na, K, hydroxy – peptide etc.) and 5% water.
The root of the tooth is covered by a substance called cement, it is secreted by the cementocytes.
Each tooth has a pulp cavity which is full of pulp.
The pulp consists of connective tissues, blood capillaries, nerves & odontoblasts.
The pulp cavity Opens out through an apical pore which gets closed later on.

1.2. Pharynx:

The buccal cavity opens into pharynx which is comparatively less distinct in mammals.
The dorsal part of the pharynx is called as nasopharynx whereas its ventral part is termed as the oropharynx.
The pharynx is lined by stratified squamous epithelium.
Posteriorly, the pharynx has 2 openings viz., gullet and glottis.
The oropharynx opens into the oesophagus through the gullet.

1.3. Oesophagus:

The oesophagus passes through the neck & thorax. It pierces through the diaphragm and finally opens into the stomach.
Its length depends upon the length of the neck. In man, it’s length is about 25 cm.
Internally, it has many longitudinal folds.
The anterior part of the oesophagus is made up of striated (Voluntary) muscles.
Rest part is made up of smooth muscles.
The wall of Oesophagus consists of follower layers:
1. Serosa: Outermost layer
2. Musculature: It includes an outer layer of longitudinal muscles and an inner layer of circular muscles.
3. Submucosa: It is made up of connective tissues. It has blood vessels, nerves and lymph ducts.
4. Mucosa: It is the innermost layer which is made up of stratified squamous epithelium.

1.4. Stomach:

It is a bag-like structure which is situated in the anterior left part of the abdominal cavity. just below the diaphragm.
Its anterior part is called the fundus, middle part as body and posterior part as pyloric.
There is a cardiac sphincter (valve) between the oesophagus & the stomach.
Similarly, the basal opening of the stomach is regulated by a pyloric sphincter.
The main body forms 80% of the stomach and it secretes most of the part of the gastric juice.

Histology of Stomach:
The wall of the stomach consists of following layers from outside to inside –
(1) Serosa: It is modified visceral peritoneum which is made up of squamous epithelium.

(2) Musculature:

It includes an outer layer of longitudinal muscles and an inner layer of circular muscles. There is an Aurabach plugin between the longitudinal and circular muscles.
The stomach has an additional layer of oblique muscles.

(3) Sub-mucosa:

It is the most developed layer which is made up of connective tissues. In addition, it includes blood vessels, nerves, lymph vessels & gland cells.
There is a Meissner’s plugin the sub-mucosa.

(4)Muscularis mucosa:

It is situated in the sub-mucosa.
It consists of three layers viz., the outer layer of circular muscles, a middle layer of longitudinal muscles & an inner layer of circular muscles.

(5) Mucosa:
It is the innermost layer which is made up of columnar epithelium.
It includes many Goblet cells to secrete mucously.
It also contains oxyntic cells of parietal cells which secrete dilute HCl.
It also bears zymogen or peptic or chief cells which secrete gastric enzymes.

1.5. Intestine:

It is the longest part of the alimentary canal. Its the length in the rabbit is 4 to 5 metre and in human beings is 7 to 8 metre.
The intestine is divisible into four parts viz., duodenum, jejunum, ileum or small intestine & large intestine.

1.5.1.
Intestine:

The pylorus part of the stomach opens into the intestine.
Its length is about 7.5 meter. It consists of three parts:

(1) Duodenum:

It is the anterior-most part of the intestine which is U – shaped & it is of 15 cm in length.
The gall bladder gives out a bile duct which is also called a Duodenum.
There is a pancreas in between the limbs of the duodenum which is irregular in shape.
The pancreas opens into the middle part of the duodenum through a pancreatic duct
which is also called as Wirsung’s duct.
In human beings, the bile duct & the pancreatic duct open into an ampulla of Vator which in turn open into the proximal part of the duodenum. This opening is guarded by a sphincter of Odi.
Histology of Duodenum:
The histology of duodenum is similar to the histology of the stomach except the following:
1. The musculature of the duodenum lack oblique muscles.
2. The sub-mucosa layer of the duodenum is provided with special Brunner’s glands which secrete mucously.
3. The mucosa layer of the duodenum forms many crypts of Leiberkuhn. They have a large number of argentaffin cells.

(2) Jejunum: It is a middle and smaller part.

(3) Ileum:

It is the longest part of the intestine which is coiled. The coiled shape is maintained with the help of mesenteries.
It’s musculature lack the oblique muscles and its submucosa is without Burner’s glands.
Its mucosa layer forms many Villi & Crypts of Leiberkuhn. The connective tissues in the villi are called lamina propria which consists of B.Vs, & lymph vessels.
There are Peter’s patches in the submucosa which are lymph nodes and form lymphocytes.
Its length is about 6.5 meter.
The intestinal cavity has special longitudinal folds which are called as folds of Kackring.
The mucosa of the ileum has special Paneth’s cells which secrete intestinal juice or succus entericus.

1.5.2. Large Intestine:

This pan of the intestine is shorter but its diameter is large.
The large intestine includes caecum, colon and rectum.

(1) Caecum:

It is a special structure which is found in herbivorous animals to digest cellulose.
In human beings. the caecum is found in the form of the vestigial vermiform appendix. Its opening remains closed by a sphincter.
The ileocaecal valve is also vestigial which get incorporated into the wall. It contains lymph nodes which form lymphocytes.

(2) Colon:

Its length is 1.5 to 2 metre in human beings.
Human colon has four parts –
1. Ascending colon.
2. Transverse colon.
3. Descending colon.
4. Sigmoid colon.
Its outer surface has a Longitudinal muscle band which is called a taenia coil.

(3) Rectum:

It is the last part of the alimentary canal. Its length is 18 – 20 cm in human beings.
The terminal part of the rectum is called an anal canal which leads outside through the anus.
Both the anal canal and anus are ectodermal in origin.
The anus is controlled by an anal sphincter which is made up of striated muscles.
The rectum is without serosa and mesenteries.

Question 2.
Describe the structure of human tooth giving labelled diagram.
Answer:
Structure of human tooth:

The mammalian teeth are thecodont.
The mammalian teeth are diphyodont i.e. there are two sets of the teeth in the life viz.,
1. Milk or Deciduous teeth – the There number is 20.
2. Permanent or Non-deciduous teeth – the There number is 32.
The mammalian teeth are heterodont i.e. 4 types of teeth are found viz.,
1. Incisors
2. Canines
3. Premolars
4. Molars
Last four molars are called wisdom teeth.
Dental formula:
1. The dental formula denotes position, number & type of teeth in the jaws.
2. The dental formula denotes teeth in half of the jaws.
3. A total number of teeth can be obtained by doubling the dental formula.
4. The dental formula of Man
  - Infant ⇒ 12/2, C 1/1, Pm 0/0, M2/2 ⇒ 10 × 2 ⇒ 20
  - Adult ⇒ 12/2, C 1/1, Pm 2/2, M 3/3 ⇒ 16 × 2 ⇒ 32

(2) Neck: It is the middle part of the tooth which is covered by the gums.

(3) Root:

It remains embedded in the bony socket.
The number of the root in the incisors & canines is 1 – 1, in premolars is 2 and in molars is 3 – 5.
The root is bounded by a periodontal membrane.
The tooth is mainly made up of dentine. It is provided with canaliculi.
The crown part of the tooth is covered by a hard substance, the enamel which is formed by ectodermal ameloblasts.
It is the hardest substance in the body which consists of 95% inorganic substances (calcium phosphate, Mg, Na, K, hydroxy – peptide etc.) and 5% water.
The root of the tooth is covered by a substance called cement, it is secreted by the cementocytes.
Each tooth has a pulp cavity which is full of pulp.
The pulp consists of connective tissues, blood capillaries, nerves & odontoblasts.
The pulp cavity Opens out through an apical pore which gets closed later on.

Question 3.
Where & how the digested food is absorbed in human beings.
Answer:
Absorption of the digested food:

There is the absorption of the digested food in the ileum into the blood with the help of active transport.
The villi provide an increased surface for the absorption. The Millikin in hormone enhances absorption by increasing villi movements.
There is about 45 lakh of villi in the ileum of human beings.
The monosaccharides (glucose, galactose, fructose, mannose etc.) are absorbed directly into the blood by active transport in the presence of water.
The amino acids are also absorbed directly into the blood by active transport.
Alcohol is absorbed by diffusion in the whole alimentary canal.
The fatty acids before the absorption form an emulsion in the presence of bile salts which is called micelles.
These micelles are taken up by the epithelial cells with the help of pinocytosis.
The epithelial cells pack these fatty acids in small packets which are called chylomicrons.
The diameter of the chylomicron is about 1µ. The chylomicrons are released into the lacteals by exocytosis.
The chylomicrons from the lymph reach into the blood at the junction between subclavian & jugular veins.
The water-soluble vitamins are absorbed directly into the blood by diffusion.
Absorption of the vitamin B12 needs the presence of a castle factor.
Fat-soluble vitamins are absorbed with the help of bile salts like the absorption of the fatty acids.
About 20 litres of water can be absorbed in human intestine per day.

Question 4.
Explain intestinal digestion in human beings.
Answer:
Digestion in Duodenum:

The entry of chyme into the duodenum results in the secretion of bile juice.
The bile juice is greenish-yellow digestive juice which is alkaline (pH – 7 to 8). It is without any digestive enzyme. In human beings, about 1 litre of the bile juice is produced every day.
Chemical composition of the bile-The bile juice includes the following substances –
- Water – 89.0%
- Bile salts – 6.0% (Taurocholate & Glycocholate)
- Bile pigments – 3.5% (Bilirubin and Biliverdin)
- Cholesterol – 0.8%
- Inorganic salts – 0.7%

Functions of the bile juice:

It neutralizes the acidic medium of the chyme.
The bile salts perform emulsification of the fats.
It acts as a bactericidal.
The bile salts help in the absorption of the fatty acids.
It excretes an excess of the cholesterol.
It excretes bile pigments which are formed in the liver by the degradation of the haemoglobin.
The duodenum also receives the pancreatic juice.
The pancreatic juice is a colourless & alkaline juice (pH 8). It contains 98.5% water & 1.5% of solids. In human beings, 0.5 to 1 litre of pancreatic juice is secreted per day.

The pancreatic juice has 2 parts –
(1) Salt part:

It is under the control of the secretin hormone.
It contains chloride, carbonate & bicarbonates of sodium, potassium & calcium.
It makes the chyme alkaline.

(2) Enzymatic part:

It is secreted under the control of pancreas.
It includes the following main enzymes –
1. Trypsinogen
2. Chymotrypsinogen
Active trypsin & chymotrypsin covert the proteins completely into peptones & proteoses.
The trypsin breaks the peptide bonds formed between the arginine and lysine amino acids.
Similarly, the chymotrypsin breaks the peptide bonds formed between the aromatic amino acids.

(3) Pancreatic amylase:

It is also called as amylopsin.
It converts simple polysaccharides into disaccharides.

(4) Lipase:

It is also called as steapsin.
It converts emulsified fats into fatty acids & glycerol.
Digestion in the duodenum results in the formation of chyle which enters into the ileum.

Digestion in Ileum:

The entry of the chyle into ileum results in the secretion of two hormones viz., Enterokinin & Villikrinin.
The entertaining acts on the intestinal glands & results in the secretion of intestinal juice or succus entericus.
The intestinal juice is an alkaline juice (pH – 8). It contains 98.5% water & 1.5% solids.
It includes many enzymes such as invertase, maltase, lactase, lipase, aminopeptidase, nuclease, nucleotidase, nucleosidase.
1. Sucrose + Sucrase → Glucose + Fructose
2. Maltose + Maltase → Glucose + Glucose
3. Lactose + Lactase → Glucose + Galactose
4. Emulcified fats + Lipase → Fatty acids + Glycerol
5. Peptones + Amino peptidases → Amino acids & Protcoses.
In the ileum, there is complete digestion of all substances except the cellulose.

RBSE Solutions for Class 12 Biology

RBSE Solutions for Class 12 Biology Chapter 34 Menstrual Cycle in Woman

August 3, 2019 by Prasanna Leave a Comment

Rajasthan Board RBSE Class 12 Biology Chapter 34 Menstrual Cycle in Woman

RBSE Class 12 Biology Chapter 34 Multiple Choice Questions

Question 1.
The reproductive cycle in a mammalian female is called –
(a) Oestrous cycle
(b) Menstrual cycle
(c) Both of the above
(d) None of these
Answer:
(c) Both of the above

Question 2.
How many days (average) are required to complete a menstrual cycle in women?
(a) 18 days
(b) 28 days
(c) 38 days
(d) 12 days
Answer:
(b) 28 days

Question 3.
During the menstrual cycle, how many days the menstruation occurs.
(a) 3 – 5 days
(b) 8 – 12 days
(c) 13 – 20 days
(d) 26 – 30 days
Answer:
(a) 3 – 5 days

Question 4.
The essential hormone for ovulation is –
(a) FSH
(b) LH
(c) Estrogen
(d) Oxytocin
Answer:
(b) LH

Question 5.
Essential hormone for milk ejection is –
(a) FSH
(b) LH
(c) Estrogen
(d) Oxytocin
Answer:
(d) Oxytocin

RBSE Class 12 Biology Chapter 34 Very Short Answer Type Questions

Question 1.
In how many days one menstrual cycle completes?
Answer:
28 to 30 days

Question 2.
Write names of reproductive cycles found in mammalian females.
Answer:
Menstrual cycle and Estrus cycle.

Question 3.
Which hormone secretes during parturition?
Answer:
Oxytocin and Relaxin.

Question 4.
Which hormones are secreted during the gestation period?
Answer:
Progesterone and LH.

RBSE Class 12 Biology Chapter 34 Short Answer Type Questions

Question 1.
What is Estrous cycle?
Answer:
Cycle:

It is exhibited by all eutherian mammalian females except the order -primate.
The mammalian females which exhibit one estrus cycle in one breeding season are called as monoestrous.
Example: Dogs, Fox, Bats, Deer etc.
The mammalian females which exhibit two or more oestrous cycles in one breeding season are called polyestrous.
Example: Rat, squirrel, cow, pig, horse, cat, sheep rabbit etc.
The oestrous cycle is studied with the help of vaginal smears.
The duration of various phases of the oestrous cycle varies from species to species. In the rat, it is from 4 to 5 days and in the rabbit is 16 to 17 days.

The oestrous cycle has 4 phases –
1. Diestrus phase:

It is also called as anestrus phase.
It is the longest phase & its duration is of 60 to 70 hours.
The ovary is without Graffian follicles.
The uterine gland is thin, small & inactive.
The vaginal smear shows leucocytes.
During the non-breeding season, the female remains in the diestrus phase.

2. Proestrus phase:

It is the smallest phase. Its duration is 1/2 to 5 hours.
There is no growth of ovarian follicles.
Vaginal smear exhibits epithelial cells.
The uterine glands begin to increase in number & size.
The thickness & contractability of the uterine wall begins to increase.

3. Oestrous phase:

Its duration in the rat is 9 to 15 hours.
It is also called a heat period.
The basal temperature of the body is increased.
Formation of Graffian follicles in the ovary.
The vaginal smear shows the presence of cornified cells.
The maximum level of estrogen in the blood.
Ovulation takes place.

4. Post-Estrus or metestrus phase:

Its duration is of 10 to 14 hours.
The vaginal smear shows cornified cells & leucocytes.
The maximum level of progesterone in the blood.
Formation of Corpus luteum in the ovaries.
If there is fertilization, the female remains in metestrus till the parturition.
The oestrous cycle repeats if there is no fertilization and after parturition.

Question 2.
What is the Menstrual cycle?
Answer:
Menstrual cycle:

It is found only in primate females.
Its duration is 28 to 30 days in a woman and 35 days in the chimpanzee.
In woman, the menstrual cycle begins at an age of 12 years which is called menarche.
The menstrual cycle ceases naturally at an age of 45 to 50 years which is called menopause.

The menstrual phase has 4 phases of viz.

Menstrual phase
Follicular phase or Proliferative phase
Ovulatory phase or recovery phase
Luteal phase or secretory phase

Question 3.
Which is the Ovulation phase?
Answer:

Oestrous phase:
It is a phase of Menstrual cycle.
Its duration in the rat is 9 to 15 hours.
It is also called a heat period.
The basal temperature of the body is increased.
Formation of Graffian follicles in the ovary.
The vaginal smear shows the presence of cornified cells.
The maximum level of estrogen in the blood.
Ovulation takes place.

RBSE Class 12 Biology Chapter 34 Essay Type Questions

Question 1.
Describe the Menstrual cycle in detail.
Answer:
Menstrual cycle:

It is found only in primate females.
Its duration is 28 to 30 days in the woman and 35 days in the chimpanzee.
In woman, the menstrual cycle begins at an age of 12 years which is called menarche.
The menstrual cycle ceases naturally at an age of 45 to 50 years which is called menopause.

The menstrual phase has 4 phases of viz.
1. Menstrual phase:

Its duration is of 3 to 5 days in a woman.
Term menstruation means bleeding.
During this phase, the blood is released along with dead ovum & pieces of the uterine endometrium.
The ovary has immature follicles & corpus Albicans.
The body has less estrogen & the progesterone is almost absent.

2. Follicular phase or Proliferative phase:

Its duration is of 8 to 10 days.
Maximum estrogen in the blood.
Formation of Graffian follicles up to the end of this phase.
Increased thickness of the uterine wall and increased number of uterine B.Vs. & uterine glands.
Blood FSH is increased but blood LH is reduced.

3. Ovulatory phase or recovery phase:

There is ovulation which occurs 14th + 2 days in a woman.
The ovary has burst Graffian follicle.
FSH & Estrogen get lowered slightly.

4. Luteal phase or secretory phase:

It is also called as the pre-menstrual phase.
It is the longest phase. Its duration in a woman is 12 to 16 days.
The ovary shows fully developed corpus luteum.
Myomatrium & endomatrium are maximum developed.
Maximum estrogen, progesterone & LH in the blood.
Uterine glands are completely developed & corkscrew-shaped.
The female remains in lateral phase till parturition.
If there is no fertilization, the menstrual cycle is repeated.
Increase in body temperature.

Question 2.
Write an essay on Parturition in Human.
Answer:
Parturition:

In the rabbit, man & other eutherians embryonic development completes in the uterus which is followed by the birth of young ones. It is called parturition.
The duration between the fertilization & the parturition is called gestation.
The gestation is different in, the different species.
In the rabbit, it is of 28 – 30 days and in man is 270 to 280 days. In the rabbit, the young ones are hairless, blind & deaf.
They become normal in 5 to 7 days. Parturition is a hormonal process which involves many hormones.
At the completion of the embryonic development, the pituitary increases the secretion of FSH, decreases the secretion of
LH & begins the secretion of oxytocin & MH.
Decreased LH, in turn, decreases the secretion of progesterone.
As a result, the placenta gets dissolved and the foetus separates from the uterine wall.
Increased FSH restarts oogenesis.
Oxytocin is the main hormone of parturition.
It causes labour pains by contracting the uterine muscles.
The contractions in the uterus push the foetus into the vagina.
Relaxin in man is secreted by the corpus luteum and.in rabbit by the placenta.
This hormone provides broad passage for parturition by relaxing pubic symphysis of the pelvic girdle.

Question 3.
Write an essay on Lactation in Human.
Answer:
Lactation:

Prolactin (PRL) hormone is secreted by the anterior pituitary gland during gestation period from 5th week up to parturition is responsible for the development of mammary glands.
It also promotes the secretion of milk from the breasts after the birth of the child. Besides this placenta also secretes human chorionic somatotropin (HCST) which is also helpful in milk secretion.
The secretion of prolactin from the anterior pituitary is stimulated by Oxytocin.
Up to three days since. parturition, the secretion of breasts is yellow fluid which is rich in proteins and lactose.
This fluid is called colostrum. It contains Immunoglobulins (IgA), which develops innate immunity in the newborn child.
Milk Secretion – milk → alveoli → ductule → mammary duct → mammary sinus → lactiferous duct → breast nipple → child sucks milk.
The neuroendocrine reflex is required for milk secretion.
Oxytocin hormone secretion from the pituitary gland is responsible for milk secretion.
When a newborn child sucks the milk of mother than somatic neural reflex reaches to the hypothalamus and it initiates oxytocin secretion from the posterior pituitary.
It facilitates milk ejection by contracting epithelial muscular cells of mammary gland so milk flow in tubules and child receive milk from nipples.
Prolactin secretion of the anterior pituitary is responsible for the synthesis of milk in the mammary glands.
While oxytocin hormone is responsible for milk secretion from mammary glands.
Milk secretion is a Conditional reflex in which milk secretion occurs by the combined action of Suckling reflex and Ejection reflex.
Breastfeeding is essential for 6 months after parturition for proper development of the child.

RBSE Solutions for Class 12 Biology

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RBSE Solutions for Class 12 Biology

Rajasthan Board RBSE Class 12 Biology Chapter 30 Man-Movement & Locomotion

RBSE Class 12 Biology Chapter 30 Multiple Choice Questions

RBSE Class 12 Biology Chapter 30 Very Short Answer Type Questions

RBSE Class 12 Biology Chapter 30 Short Answer Type Questions

RBSE Class 12 Biology Chapter 30 Essay Type Questions

Rajasthan Board RBSE Class 12 Biology Chapter 23 Man-Respiratory System

RBSE Class 12 Biology Chapter 23 Multiple Choice Questions

RBSE Class 12 Biology Chapter 23 Very Short Answer Questions

RBSE Class 12 Biology Chapter 23 Short Answer Questions

RBSE Class 12 Biology Chapter 23 Essay Questions

Rajasthan Board RBSE Class 12 Biology Chapter 33 Embryonic Development in Man

RBSE Class 12 Biology Chapter 33 Multiple Choice Questions

RBSE Class 12 Biology Chapter 33 Very Short Answer Type Questions

RBSE Class 12 Biology Chapter 33 Short Answer Type Questions

RBSE Class 12 Biology Chapter 33 Essay Type Questions

Rajasthan Board RBSE Class 12 Biology Chapter 22 Man-Digestive System

RBSE Class 12 Biology Chapter 22 Multiple Choice Questions

RBSE Class 12 Biology Chapter 22 Very Short Answer Questions

RBSE Class 12 Biology Chapter 22 Short Answer Questions

RBSE Class 12 Biology Chapter 22 Essay Type Questions

Rajasthan Board RBSE Class 12 Biology Chapter 34 Menstrual Cycle in Woman

RBSE Class 12 Biology Chapter 34 Multiple Choice Questions

RBSE Class 12 Biology Chapter 34 Very Short Answer Type Questions

RBSE Class 12 Biology Chapter 34 Short Answer Type Questions

RBSE Class 12 Biology Chapter 34 Essay Type Questions

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