Biology

Reproduction in Organisms

Question:

Suggest a possible explanation why the seeds in a pea pod are arranged in a row, whereas those in tomato are scattered in the juicy pulp.

Answer:

In a fruit, seed arrangement depends on type of placentation. Pea and tomato shows different placentation. Pea shows marginal placentation while tomato shows axile placentation.

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Reproduction in Organisms

Q 1.

Give reasons as to why cell division cannot be a type of reproduction in multicellular organisms.

Q 2.

Explain why meiosis and gametogenesis are always interlinked?

Q 3.

Differentiate between a zoospore and a zygote.

Q 4.

Why is reproduction essential for organisms?

Q 5.

Match the organisms given in Column ‘A' with the vegetative propagules given in column ‘B'.
ncert-exemplar-problems-class-12-biology-reproduction-in-organisms-5

Q 6.

Between an annual and a perennial plant, which one has a shorter juvenile phase? Give one reason.

Q 7.

In the figure given below, mark the ovule and pericarp.
ncert-exemplar-problems-class-12-biology-reproduction-in-organisms-3

Q 8.

Is it possible to consider vegetative propagation observed in certain plants like Bryophyllum, water hyacinth, ginger etc., as a type of asexual reproduction? Give two/three reasons.

Q 9.

Is there a relationship between the size of an organism and its life span? Give two examples in support of your answer.

Q 10.

Why are offspring of oviparous animals at a greater risk as compared to offspring of viviparous animals?

Q 11.

Why do we refer to’offspring formed by asexual method of reproduction as clones?

Q 12.

In a developing embryo, analyse the consequences if cell divisions are not followed by cell differentiation.

Q 13.

Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?

Q 14.

Describe the post-fertilization changes in a flower.

Q 15.

Define:
(a)Juvenile phase
(b)Reproductive phase
(c)Senescent phase.

Q 16.

Which of the followings are monoecious and dioecious organisms?
a. Earthworm ——————–
b. Chara ——————–
c. Marchantia ——————-
d. Cockroach ——————

Q 17.

Fertilisation is not an obligatory event for fruit production in certains plants'. Explain the statement.

Q 18.

Rose plants produce large, attractive bisexual flowers but they seldom produce Suits. On the other hand a tomato plant produces plenty of fruits though they have small flowers. Analyse the reasons Tor failure of fruit formation in rose.

Q 19.

Rearrange the following events of sexual reproduction in the sequence in which they occur in a flowering plant:  embryogenesis, fertilisation, gametogenesis, pollination.

Q 20.

Define external fertilization. Mention its disadvantages.

Q 21.

Which Is a better mode of reproduction: sexual or asexual? Why?

Q 22.

Is the presence of large number of chromosomes in an organism a hindrance to sexual reproduction? Justify your answer by giving suitable reasons.

Q 23.

In haploid organisms that undergo sexual reproduction, name the stage in the life cycle when meiosis occurs. Give reasons for your answer.

Q 24.

Honeybees produce their young ones only by sexual reproduction. Inspite of this, in a colony of bees we find both haploid and diploid individuals. Name the haploid and diploid individuals in the colony and analyse the reasons behind their formation.

Q 25.

Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?

Q 26.

Although sexual reproduction is a long drawn, energy-intensive complex form of reproduction, many groups of organisms in Kingdom Animalia and Plantae prefer this mode of reproduction. Give at least three reasons for this.

Q 27.

Suggest a possible explanation why the seeds in a pea pod are arranged in a row, whereas those in tomato are scattered in the juicy pulp.

Q 28.

Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n).
(a)Ovary ————————
(b)Anther ————————
(c)Egg ————————
(d)Pollen ————————
(e)Male gamete ————————
(f)Zygote ————————

Q 29.

Why is the offspring formed by asexual reproduction referred to as clone?

Q 30.

Although potato tuber is an underground part, it is considered as a stem. Give two reasons.

Q 31.

How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?

Q 32.

The number of taxa exhibiting asexual reproduction is drastically reduced in higher plants (angiosperms) and higher animals (vertebrates) as compared with lower groups of plants and animals. Analyse the possible reasons for this situation.

Q 33.

What do the following parts of a flower develop into after fertilisation?
a. Ovary
b. Ovules

Q 34.

Justify the statement Vegetative reproduction is also a type of asexual reproduction'.

Q 35.

Do all the gametes formed from a parent organism have the same genetic composition (identical DNA copies of the parental genome)? Analyse the situation with the background of gametogenesis and provide or give suitable explanation.

Q 36.

In the figure given below, the plant bears two different types of flowers marked ‘A' and ‘B Identify the types of flowers and state the type of pollination that will occur in them.
ncert-exemplar-problems-class-12-biology-reproduction-in-organisms-2

Q 37.

Why do gametes produced in large numbers in organisms exhibit external fertilisation?

Q 38.

Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?

Q 39.

Mention two inherent characteristics of Amoeba and yeast that enable them to reproduce asexually.

Q 40.

The probability of fruit set in a self-pollinated bisexual flower of a plant is far greater than a dioecious plant. Explain.

Q 41.

What is vegetative propagation? Give two suitable examples.

Q 42.

With which type of reproduction do we associate the reduction division? Analyse the reasons for it.

Q 43.

What is % bisexual flower? Collect five bisexual flowers from your neighbourhood and with the help of your teacher find out their common and scientific names.

Q 44.

Which of the following is a post-fertilisation event in flowering plants?
(a) Transfer of pollen grains
(b) Embryo development
(c) Formation of flower
(d) Formation of pollen grains

Q 45.

Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?

Q 46.

List the changes observed in an angiosperm flower subsequent to pollination and fertilisation.

Q 47.

Draw the sketches of a zoospore and a conidium. Mention two dissimilarities between them and alt least one feature common to both structures.

Q 48.

Enumerate the differences between asexual and sexual reproduction. Describe the types of asexual reproduction exhibited by unicellular organisms.

Q 49.

Differentiate between gametogenesis from embryogenesis.

Q 50.

Differentiate between (a) oestrus arid menstrual cycles; (b) ovipary and vivipary. Cite an example for each type.