What is DNA? - Science


What is DNA?



Deoxyribonucleic acid (DNA) is a genetic material found in all the living organisms except few viruses.

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2015-2016 (March) Delhi Set 2


What do you mean by DNA?

Name the scientist who put forward the most popular model of DNA.

Draw a diagram of DNA showing genes.

State the importance of DNA copying.

Explain the importance of reproduction in organisms.

Indicate whether the following statement is True (T) or False (F).
Egg laid after fertilization is made up of a single cell. ( )

Indicate whether the following statement is True (T) or False (F).

Amoeba reproduces by budding. ( )

Fill in the blanks:

Production of new individuals from the vegetative part of parent is called ________.

Describe the different methods of asexual reproduction. Give examples.

Match items in Column I with those in Column II:

Column I Column II
Bud Maple
Eyes Spirogyra
Fragmentation Yeast
Wings Bread mould
Spores Potato

Tick (√ ) the correct answer:

A spore producing plant is

Find the odd one out:

Amoeba, Euglena, Planaria, Paramoecium


What is the name of the reproductive process :
which involves two parents?

Why are budding, fragmentation and regeneration, all considered to be asexual type of reproduction?

Fill in the following blank with suitable word :

the process of...........ensures continuity of life on earth.

Why is variation during reproduction beneficial to the species but not necessarily for the individual?

Reproduction is essential for living organisms in order to ______

Name two animals which undergo external fertilisation.

What type of fertilisation takes place in birds?

Imagine all the seeds produced by a plant happen to fall under the same plant and sprout into new plants. Mention any two problems that will be faced by the new plants.

State whether the following statement is true (T) or false (F):

Producing life is called respiration.

State whether the following statement is true (T) or false (F):

Dogs and cats reproduce from two parents.

State whether the following statement is true (T) or false (F):

Most organisms have the capacity of regeneration in some or the other way.

Find the odd-one out, giving reason.

Gamete, budding, fragmentation, regeneration.

Define the following:


Why is reproduction necessary for living organisms?

Differentiate between the following:

Asexual reproduction and sexual reproduction.

Tick (✓) the correct answer:
Bryophyllum can reproduce by its

What is the role of the seminal vesicles and the prostate gland?

The daughter cells produced by asexual reproduction are genetically identical to the parent cell.

Match the following:

Column ‘I’ Column ‘II’
(1) Inhibits plant growth
(a) Breaks large fat globules into smaller ones
(2) Cytokinins
(b) Auxins
(3) Cellular respiration
(c) Mitochondria
(4) Bile
(d) Promote cell division
(e) Abscisic acid

What do you mean by ‘Connecting Links’? Give one example.

Explain the term Reproduction.

Explain the term: Pollination. 

By which process do green plants synthesize their food?

Name the factors which take part in this process.

Answer the following question.
The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not necessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of the population.

(a) List two common signs of sexual maturation in boys and girls.
(b) What is the result of reckless female foeticide?
(c) Which contraceptive method changes the hormonal balance of the body?
(d) Write two factors that determine the size of a population.

Multiple choice question.

In ovule, meiosis occurs in ______

If diploid chromosome number in a flowering plant is 12, then which one of the following will have 6 chromosomes?

Multiple choice question.

Point out the odd one.

Sporoderm is made up of ______.

In vitro pollen germination and pollen tube elongation can be induced by ______.

______ is an example of helobial endosperm.

The example of dicot endospermic seed is ______.

What is hilum with respect to ovule?

Which is the most common type of endosperm in angiospermic families?

Explain heterostyly and herkogamy with suitable example.

Reproductive part of a plant is ______.

Write two types of reproduction in plants.

The plant which propagates with the help of its leaves is ______.

Planaria reproduces asexually by ______.

Match the following.

Column I Column II
Fission Spirogyra
Budding Amoeba
Fragmentation Yeast

What will happen if you cut planaria into small fragments?

Why is vegetative propagation practiced for growing some type of plant?

Name two organisms that reproduce through budding.

Which of the following is diploid at the time of fertilization in a gametophyte of a normal angiosperm?

Identify the chromosome number of the endosperm in the following case. In an angiosperm a female plant having 2n = 24 is crossed with a male plant having 2n = 12.

Assertion and Reason types of Question.

Assertion: In potatoes, shoot arises from eyes.
Reason: Eyes represent the buds.

Assertion and Reason types of Question.

Assertion: In Banyan prop roots grow horizontally from the tree.
Reason: They give additional support to the tree.

Assertion and Reason types of Question.

Assertion: Corm is a condensed form of Bulb.
Reason: It has dry and fleshy scale leaves.

Which of the following nucleus is unlike other nuclei in the female gametophyte of angiosperms?


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