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प्रश्न
Name the scientist who put forward the most popular model of DNA.
उत्तर
James Watson and Francis Crick proposed the double helix or spiral staircase structure of the DNA molecule in 1953. They were awarded the Nobel Prize for this discovery in 1962.
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संबंधित प्रश्न
Draw a diagram of DNA showing genes.
Define reproduction.
What is DNA?
Why is DNA copying an essential part of the process of reproduction?
Write down the different methods of asexual reproduction.
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.
What are the two general methods of reproduction in organisms?
Why is variation during reproduction beneficial to the species but not necessarily for the individual?
Asexual reproduction is :
(a) a fusion of specialised cells
(b) a method by which all types of organisms reproduce
(c) a method producing genetically identical offspring
(d) a method in which more than one parent are involved
In asexual reproduction, two offsprings having the same genetic material and the same body features are called :
(a) callus
(b) twins
(c) clones
(d) chromosomes
What type of fertilisation takes place in fish?
Why is reproduction necessary for living organisms?
Differentiate between the following:
Asexual reproduction and sexual reproduction.
Name the part of the cell where DNA is located?
Bryophyllum can reproduce by its ______.
What do you mean by ‘Connecting Links’? Give one example.
Explain the term: Pollination.
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.
Insect pollinated flowers usually posses ______
Which of the following types require pollinator but the result is genetically similar to autogamy?
The number of meiotic and mitotic divisions necessary for development of female gametophyte in angiosperms is ______.
Identify the odd one with respect to pollinating agent.
Self-incompatibility is found in flowers of plants _______.
The single shield-shaped cotyledon in monocot seed is known as ______.
What is hilum with respect to ovule?
Draw a well labelled diagram of T.S. anther.
Seminal fluid is ______ in nature.
The average period of pregnancy in human lasts for ______ days of pregnancy.
What is the function of inner cell mass?
Write two types of reproduction in plants.
Planaria reproduces asexually by ______.
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?
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: Corm is a condensed form of Bulb.
Reason: It has dry and fleshy scale leaves.
Define the following term:
Reproduction
