Biology 2019

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Question Paper with Complete Solution

PART - A

Answer the following questions in one word or one sentence each;

1. Name the reproductive cycle that occurs in non-primates.

Ans: Oestrus Cycle

2. Name the layer of the uterus that exhibits strong contractions during parturition.

Ans: The myometrium exhibits strong contraction during the delivery of the baby.

3. Which chromosome of man has the least number of genes?

Ans: 'Y' chromosome

4. Write the infectious form of plasmodium which enter the human body through a mosquito bite.

Ans: 'Sporozoite'

5. Give an example for an inter-specific hybrid animal.

Ans: Mule – The mule is a progeny of a female horse and a male donkey.

6. Write the scientific name of the source organism for citric acid.

Ans: Aspergillus niger

7. Mention a gene that codes for an insecticidal protein in Bt cotton.

Ans: cry II Ab

8. Name the plasmid present in Agrobacterium tumefaciens.

Ans: Agrobacterium tumefaciens cell contains a plasmid known as the Ti (tumor-inducing) plasmid.

9. What is the main aim of the Montreal protocol?

Ans: To check the emission of ozone-depleting substances.

10. Name the type of food chain that is the major conduit for energy flow in an ecosystem.

Ans: Grazing food chain (GFC)

 

PART - B

Answer any five of the following questions in 3 to 5 sentences each wherever applicable;

11. What is embryogenesis? Mention two important events that occur during embryogenesis.

Ans: The process of development of an embryo from the zygote.

 

Two important events that occur during embryogenesis are cell division and cell differentiation.

12. Define point mutation. Give an example for point mutation.

Ans: Point mutation is a change in a single base pair of DNA by substitution, deletion, or insertion of a single nitrogenous base.

An example of point mutation is sickle cell anaemia. It involves a mutation in a single base pair in the beta-globin chain of haemoglobin pigment of the blood.

13. What are the conclusions drawn by T. H. Morgan from the crossing experiments in Drosophila with respect to linkage?

Ans: The conclusions drawn by T.H. Morgan from the crossing experiment in Drosophila with respect to linkage were-

  1. The gene responsible for eye colour is located on X chromosome.

  2. The alleles responsible for eye colour are present on X chromosome. 

  3. There are two X chromosomes in females. Both X chromosomes carry an allele of the trait. 

  4. Females can be homozygous or heterozygous for the alleles.

14. What is an allergy? Name the two chemicals released by mast cells in the body during allergy.

Ans: The exaggerated or hypersensitive reaction of the immune system to certain antigens present environment is called allergy. 

Chemicals like histamine and serotonin are released from the mast cells.