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A basket of vegetables contains carrot, potato, radish and tomato. Which of them represent the correct homologous structures? (a) Carrot and potato (b) Carrot and tomato (c) Radish and carrot (d) Radish and potato

c) Radish and carrot Homologous structures are those that are related to common ancestry. Such structures have a common structural plan and are... View Article

Two pea plants one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds produce F1 progeny that have round, yellow (RrYy) seeds. When F1 plants are selfed, the F2 progeny will have a new combination of characters. Choose the new combination from the following (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green (a) (i) and (ii) (b) (i) and (iv) (c) (ii) and (iii) (d) (i) and (iii)

(b) (i) and (iv) The new combination in F2 progeny will be round, yellow and wrinkled green. The phenotypic ratio 9:3:3:1 is obtained. Parents:... View Article

New species may be formed if (i) DNA undergoes significant changes in germ cells (ii) chromosome number changes in the gamete (iii) there is no change in the genetic material (iv) mating does not take place (a) (i) and (ii) (b) (i) and (iii) (c) (ii), (iii) and (iv) (d) (i), (ii) and (iii)

(a) (i) and (ii) Evolution will not take place without change and variation the genetic material. Hence, change in genetic material and... View Article

Select the incorrect statement (a) Frequency of certain genes in a population change over several generations resulting in evolution (b) Reduction in weight of the organism due to starvation is genetically controlled (c) Low weight parents can have heavyweight progeny (d) Traits which are not inherited over generations do not cause evolution

(b) Reduction in weight of the organism due to starvation is genetically controlled The factors affecting change in genetic frequency are... View Article

A zygote which has an X-chromosome inherited from the father will develop into a (a) boy (b) girl (c) X- chromosome does not determine the sex of a child (d) either boy or girl

b) Girl Sex determination seen in humans is XY sex determination. Ovum carries X chromosome, whereas sperm can carry either X or Y chromosome.... View Article

The maleness of a child is determined by (a) the X chromosome in the zygote (b) the Y chromosome in zygote (c) the cytoplasm of germ cell which determines the sex (d) sex is determined by chance

b) The Y chromosome in zygote A male has sex chromosomes X and Y, while a female has XX as sex chromosomes . During fertilization, the mother... View Article

In human males, all the chromosomes are paired perfectly except one. This/these unpaired chromosome is/are (i) large chromosome (ii) small chromosome (iii) Y-chromosome (iv) X-chromosome (a) (i) and (ii) (b) (iii) only (c) (iii) and (iv) (d) (ii) and (iv)

c) (iii) and (iv) Y-chromosome and X-chromosome In human males, one pair called as the sex chromosomes are unpaired. Here, one is a normal... View Article

If a round, green seeded pea plant (RR yy) is crossed with wrinkled, yellow seeded pea plant, (rr YY) the seeds produced in the F1 generation are (a) round and yellow (b) round and green (c) wrinkled and green (d) wrinkled and yellow

If a round, green seeded pea plant (RRyy) is crossed with wrinkled, yellow seeded pea plant, (rrYY) the seeds produced in F1 generation are round... View Article

Which of the following statement is incorrect? (a) For every hormone, there is a gene. (b) For every protein, there is a gene. (c) For the production of every enzyme, there is a gene. (d) For every molecule of fat, there is a gene

d) For every molecule of fat there is a gene Hormone and enzymes are made up of proteins and the formation of any particular protein Is also... View Article

A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because (a) tallness is the dominant trait (b) shortness is the dominant trait (c) tallness is the recessive trait (d) height of pea plant is not governed by gene ‘T’ or ‘t’

a)Tallness is the dominant trait. A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants... View Article

Two pink coloured flowers on crossing resulted in 1 red, 2 pink and 1 white flower progeny. The nature of the cross will be (a) double fertilisation (b) self-pollination (c) cross-fertilisation (d) no fertilization

b) Self pollination In incomplete dominance, the cross between plants with pure red and white flowers results in F1 generation plants with all... View Article

Exchange of genetic material takes place in (a) vegetative reproduction (b) asexual reproduction (c) sexual reproduction (d) budding

(c) sexual reproduction In the case of asexual reproduction, only the minimal changes due to inaccuracies in DNA copying pass on to the... View Article

Describe sexually transmitted diseases and mention the ways to prevent them.

Venereal diseases which are commonly known as sexually transmitted diseases (STDs) are infectious diseases transmitted through sexual contact. It... View Article

Reproduction is essentially a phenomenon that is not for the survival of an individual but for the stability of a species. Justify.

For survival, an individual needs energy which it obtains from life processes such as nutrition and respiration. Reproduction does not provide... View Article

How does fertilisation take place? Fertilisation occurs once in a month. Comment.

The fusion of the male gamete (sperm) with the female gamete (ova) is known as fertilisation. The process of fertilisation takes place in the... View Article

What are various ways to avoid pregnancy? Elaborate any one method.

(a) Contraceptive methods are used such as (i) mechanical (ii) drugs (as pills), (iii) loop or copper T and (iv) surgical method. Contraception... View Article

Draw the diagram of a flower and label the four whorls. Write the names of gamete producing organs in the flower.

The ovary produces female gametes. Anthers produces male gametes. The important functions of flowers are mentioned below: Gametophytes develop... View Article

Distinguish between a gamete and zygote. Explain their roles in sexual reproduction.

Gamete Zygote Formed after Meiosis Formed by the fusion of two gametes. Gametes produces haploid number of chromosomes produces diploid... View Article

Distinguish between pollination and fertilisation. Mention the site and product of fertilisation in a flower. Draw a neat, labelled diagram of a pistil showing pollen tube growth and its entry into the ovule.

Pollination Fertilization Pollination is an external process. Fertilization can either be internal or external Pollination takes place... View Article

Write two points of difference between asexual and sexual types of reproduction. Describe why variations are observed in the offspring formed by sexual reproduction.

Sexual Reproduction Asexual Reproduction Two parents are involved One parent is involved Characteristics of both parents are inherited... View Article

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