RBSE 12th Biology Model Paper Set 2 with Answers in English

Students must start practicing the questions from RBSE 12th Biology Model Papers Set 2 with Answers in English provided here.

RBSE Class 12 Biology Model Paper Set 2 with Answers in English

Time : 2.45 Hours
Maximum Marks : 56

General Instruction to the Examinee:

1. Candidate must write first his/her Roll No. on the question paper compulsorily.
2. All the questions are compulsory.
3. Write the answer to each question in the given answer book only.
4. For questions having more than one part the answers to those parts are to be written together in continuity.
5. If there is any error/difference/contradiction in Hindi & English version of the question paper, the question of the Hindi version should be treated valid.

Section – A

(1 Mark)

Question 1.
Select the correct option of the following questions and write in notebook. (1 × 9 = 9)
(i) The term ‘pistillate’ is used for: [1]
(a) unisexual male flower
(b) unisexual female flower
(c) bisexual flower
(d) none of these
Answer:
(b) unisexual female flower

(ii) The exine of pollen grain is made of: [1]
(a) cellulose
(b) sporopollenin
(c) lignin
(d) pectocellulose
Answer:
(b) sporopollenin

(iii) When a true breeding tall plant is crossed with a true breeding short plant and F₁ produced is self-pollinated to produce F₂. Ratio of true breeding tall and true breeding short plant in F₂ will be : [1]
(a) 1 : 2
(b) 1 : 1
(c) 2 : 1
(d) 1 : 3
Answer:
(b) 1 : 1

(iv) The initiation codon in eukaryotes is : [1]
(a) AUG
(b) UGA
(c) UAG
(d) UAA
Answer:
(a) AUG

(v) Which of the following is correctly matched ? [1]
(a) Cocaine – Narcotic opiate
(b) Bhang – Analgesic
(c) Reserpine – Tranquilizer
(d) Morphine – Hallucinogen.
Answer:
(c) Reserpine – Tranquilizer

(vi) The main barrier that prevents the entry of microorganisms into our body is [1]
(a) antibodies
(b) macrophages
(c) monocytes
(d) skin
Answer:
(d) skin

(vii) Zoological name of Indian buffaloes is : [1]
(a) Bubalus bubalus
(b) Bos indicus
(c) Bos taurus
(d) Gallus gallus
Answer:
(a) Bubalus bubalus

(viii) First recombinant DNA made by: [1]
(a) Paul Berg
(b) Alec Jeffery
(c) Herry Mullis
(d) Herbert Boyer
Answer:
(a) Paul Berg

(ix) What is the source of Ti plasmid used in genetic engineering: [1]
(a) E. Coli
(b) Bacillus thuringiensis
(c) Agrobacterium thizogenes
(d) Agrobacterium tumefaciens
Answer:
(d) Agrobacterium tumefaciens

Question 2.
Fill in the blanks. (1 × 4 = 4)
(i) A …………….. embryo develops from a somatic cell. [1]
(ii) The bird Dodo became extinct because of …………….. [1]
(iii) The protein coat of virus is called …………….. [1]
(iv) Herbivores are …………….. consumers. [1]
Answer:
(i) somatic
(ii) excess hunting
(iii) small capsid
(iv) primary.

Question 3.
Give the answers of the following questions in one word or one line. (1 × 8 = 8)
(i) What is a hybrid? [1]
Answer:
The product of hybridization process which is heterozygous and mixture of both genetically dissimilar parents is called hybrid.

(ii) Define the terms ‘genotype’ and ‘phenotype’. [1]
Answer:
The genetic constitution of an organism is called genotype. The observable or external morphological characteristics of an organism constitute its phenotype.

(iii) A person free of disease is not necessarily healthy. Why? [1]
Answer:
Health is a state of complete physical, mental and social well being and not merely absence of disease.

(iv) Give one example of each of indigenous and exotic milch breeds of cows. [1]
Answer:
Indigenous breed : Sahiwal.
Exotic breed : Brown swiss.

(v) What are cosmids? [1]
Answer:
Cosmids are plasmids having the lambda and cos sequence, they are also used as a cloning vector in genetic engineering.

(vi) How the two polypeptides of insulin bond each other? [1]
Answer:
Two polypeptides chain A and B of insulin are bonded with disulfide linkage (—S—S).

(vii) In a food chain, the maximum population is of which organisms? [1]
Answer:
Producers.

(viii) Where are the largest Amazonian rain forests found? [1]
Answer:
South America.

Section – B

(1.5 Marks)

Question 4.
Name any three assisted reproductive techniques that help infertile couples to have children. Explain any one of them in brief. [1.5]
Answer:
(i) Zygote Intra Fallopian Transfer (ZIFT).
(ii) Gamete Intra Fallopian Transfer (GIFT)
(iii) Artificial Insemination Technique.
ZIFT : Zygote Intra-Fallopian Transfer is the technique in which zygote or early embryo (produced by in vitro fertilization with up to 8 blastomere is transferred into the fallopian tube of female. This principle procedure adopted for test tube baby programme).

Question 5.
Suggest the aspects of reproductive health which need to be given special attention in the present scenario. [1.5]
Answer:
The following areas need to be given special attention in the present scenario :

• People should be made aware of the negative results of population explosion, sexual abuses and sex-related crimes in the society.
• The benifits of mother and child health programmes should be within the reach of every mother and her child.
• Literacy rate should be raised for proper implementation of family welfare programmes and community health programmes.

Question 6.
You have obtained a high yielding variety of tomato. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop. [1.5]
Answer:
The procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop is :

Micropropagation : Healthy explants are taken from the tomato plants and grown in sterile conditions in special nutrient medium. The tomato plants produced from tissue culture are genetically identical to the original plant from which they are grown, so they are called somaclones. Also, through micropropagation more number of tomato plants can be produced in a short time period.

Question 7.
State what is outcrossing type of breeding. Mention on what type of cattle this is practicised. [1.5]
Answer:
Outcrossing is the technique of crossing between different breeds. This is the practice of introducing unrelated genetic material into a breeding line with recessive traits. Outcrossing allows for the recessive traits to migrate across a population.

The cattles practised this are below average in milk production and growth rate in beef cattle. It overcomes the problems of inbreeding depression.

Question 8.
What are restriction sites? Name any two restriction sites. [1.5]
Answer:
Restriction site are 6-8 nucleotide sequences present on DNA, which are out by the action of restriction enzyme. Which are very specific for their action. Name of some restriction sites are :
(1) 5′ …………. GAATTC …………. 3′ in EcoRI
3′ …………. CTTAAG …………. 5′
(2) 5′ …………. AAGCTT …………. 3′ in Hind II
3′ …………. TTCGAA …………. 5′

Question 9.
Differentiate between exonuclease and endonuclease. [1.5]
Answer:
Differences between Exonuclease and Endonuclease

	Exonuclease	Endonuclease
1.	Cleaves phosphodiester bond from ends.	Cleave phosphodiester bond b/w nucleotide chain.
2.	Require a free 3′ or 5′ end for the action.	Do not require a free 3′ or 5′ end for the action.

Question 10.
Explain any technique used for early detection of a disease. [1.5]
Answer:
Enzyme-Linked Immunosorbent Assay (ELISA) is a molecular diagnosis technique used to identify the viral, fungal, bacterium and mycoplasma etc. It is highly specific disease requires a very small amount of factors. When a pathogen enters our body, our immune response produces antibodies against it, by ELISA technique, these antibodies are detected and pathogen is identified at the early stage.

Question 11.
Explain the role of transgenic animals in production of biological products. [1.5]
Answer:
The production of transgenic animals is to improve human health and increase animal welfare by decreasing livestock disease.

• The main purpose of transgenic animals to produce is to study the regulation of genes in body.
• Transgenic animals contribute a great deal to the study of disease.
• A major objective of transgenic animals is to produce biological products.

Question 12.
Give an example of food chain which represent consumer level and trophic level. In this food chain, grass is consumed by goat which in turn is consumed by human beings. Anant states that man is the secondary consumer in this given food chain. Is Anant correct? If yes, give explanation. [1.5]
Answer:

Yes, in the given context Anant is correct. In this food chain grass is the producer which gives energy into the food chain and goat is the primary consumer. Since goat is eaten by humans, they are called secondary consumers.

Question 13.
Differentiate between grazing food chain and detritus food chain. [1.5]
Answer:

	Grazing food chain	Detritus food chain
1.	Energy is derived from the sun.	Energy is derived from organic matter produced in trophic levels of the grazing food chain.
2.	It typically entails a large population.	It is comparatively smaller.
3.	Starts with producers at the first trophic level. The plant biomass is then consumed by herbivores which inturn are consumed by different carnivores.	Starts with detritus such as dead bodies of fallen leaves and animals that are consumed by detritivores or decomposers which inturn are consumed by predators.

Question 14.
Name the three important components of biodiversity. What is species diversity? Explain with example. [1.5]
Answer:
The variety of living forms found in different ecosystems is referred to as biodiversity which includes variability in life forms from all possible sources such as air, water and land.

The three significant components of biodiversity are as follows:

• Species diversity
• Genetic diversity
• Ecosystem diversity

Species Diversity : It is the diversity of species level. For example, the western ghats have a greater amphibian species diversity than the eastern ghats. Number of species present in a unit area at given time is known as species richness of the area.

Question 15.
Define stable community. Write three features of a stable community. [1.5]
Answer:
Stable Community : A stable community is one in which the size of the population of all species remains relatively constant over time.

• Communities should have greater biodiversity for greater stability.
• It should be able to prevent invasion by alien species.
• It should be able to restore itself in a short period of time.

Section – C

(3 Marks)

Question 16.
Define sexual and asexual reproduction. Which is a better mode of reproduction: sexual or asexual? Why? [3]
Or
How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction? [3]
Answer:
Asexual Reproduction: Asexual reproduction is a type of reproduction that does not involve the formation and fusion of gametes or change in the number of chromosomes.

Sexual Reproduction : Sexual reproduction is the production of offsprings by the formation and fusion of specialized male and female cells called gametes.

Sexual reproduction is a better mode of reproduction. It allows the formation of new varients “by the combination of the genetic material from two different individuals, typically one of each sex. Sexual reproduction involves the fusion of male and female gamete to produce varients, which are not identical to their parents and to themselves. These variations allow the individual to adapt to constantly changing environment. Sexual reproduction also leads to the evolution of better suited organisms which ensure greater survival of a species.

Question 17.
What is sex determination? Explain the mechanism of sex-determination in birds with diagram. [3]
Or
What is mutation? Name different types of mutation. [3]
Answer:
Sex determination : The mechanism which determines the formation of sex (male or female) in unisexual organisms is known as sex determination.

Female heterogamy is exhibited by birds. They frave ZW-ZZ type of sex-determination.
In this type, the male is homogametic and the female is heterogametic. Therefore, there are two types of eggs i.e., with Z and with W and only one type of sperms i.e., each with Z.

When egg with Z-chromosome is fertilized by a sperm with Z-chromosome, a zygote with ZZ-chromosomes is formed.
Similarly, when egg with with ZW chromosomes (female) is W-chromosome is fertilized by a formed, sperm with Z-chromosome, a zygote

Question 18.
(a) How does the transmission of each of the following diseases take place?
(i) Amoebiasis (ii) Malaria (iii) Ascariasis (iv) Pneumonia [3]
(b) Name the causal organisms of the following :
(i) Typhoid (ii) Pneumonia (iii) Malaria, (iv) Cholera
Or
Describe AIDS disease on the basis of following points :
(i) Name of pathogen
(ii) Test for confirmation of disease
(iii) Main symptoms of disease
(iv) Ways of prevention [3]
Answer:

Name of the Disease	Transmission
Amoebiasis	Ingestion of quadri nucleated cysts of Entamoeba histolytica can cause the cysts to be passed from patient faeces via water and food.
Malaria	Plasmodium or the malarial parasite is communicated to a healthy person from a patient when a female Anopheles mosquito bites.
Ascariasis	It can be passed by ingesting contaminated water and food with the enbryonated eggs of Ascaris.

Causal Organisms :
(i) Typhoid — Salmonella typhi (Bacterium)
(ii) Pneumonia — Streptococcus
Pneumoniae (Bacterium)
(iii) Malaria — Plasmodium sp. (Protozoan)
(iv) Cholera — Vibrio cholerae (Bacterium)

Section – D

(4 Marks)

Question 19.
Describe the structure of microsporangium of a angiospermic flower. [4]
Or
Draw the diagrammatic scatch of different stages of development of microsporangium. [4]
Answer:
Structure of Microsporangium (or Pollen sac)
In a transverse section a typical microsporangium appears circular in outline. It has mainly two parts- anther wall and pollen chamber.

1. Epidermis : It is the outermost layer. It is only one cell in thickness.

2. Endothecium : It is situated below the epidermis. Mostly there is a single layer of endothecium, but sometimes it is two layered. The cells of endothecium are tangentially elongated and attain their maximum development when pollen .grains mature. The radial and inner tangential walls of these cells have characteristics fibrous thickening bonds. Due to these bonds, the endothecium cells are hygroscopic in nature, hence, play an important role in the dehiscence of anthers.

3. Middle layer : It lies inside the endothecium and made-up of 1-3 layers of thin-walled cells. The cells of these layers survive for short-time. The middle layer may store food material in some species which is utilized by pollen mother cells.

4. Tapetum : This is the innermost layer of cells with dense cytoplasm. Tapetum nourishes the developing pollen grains and secrete both enzymes and hormones. It contains two types of cells :

• Amoeboid or Periplasmodial cells
• Secretory or Glandular cells

Sporogenous Tissue : The primary sporogenous cell undergo several mitotic divisions to form microspore mother cells. A massive mass of sporogenous cells inside anther walls, called sporogenous tissue. Many cells of this tissue undergo meiosis to form microspores.

Question 20.
(a) How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material? [4]
(b) Depending upon chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesised from it (DNA or RNA). List the types of nucleic acid polymerases.
Or
Write two differences of each of the Allowing: [4]
(i) Repetitive DNA and satellite DNA.
(ii) Template strand and Loding stand.
Answer:
(a) Hershey and Chase conducted experiment onT₂-phage, a parasite on bacterium Escherichia coli and prepared two types of T₂-phages.
(i) One containing radioactive sulphur and
(ii) Other radioactive phosphorus. Both phages were made to infect normal bacteria in two separate samples. After infection the bacterial cells ruptured liberating daughter phages. By the test for radioactivity it was found that radioactive phosphorus was passed on to the daughter phages while radioactive sulphur was found in the protein coat left outside the bacterial cell.

(b) DNA template:

• DNA polymerase for DNA replication,
• RNA polymerase for RNA synthesis or transcription.

RNA template:

• RNA-dependent RNA polymerase for synthesis of RNA in some RNA viruses.
• Reverse transcriptase to synthesis cDNA (complementary DNA) over RNA template.