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प्रश्न
The eggs of frogs do not have shells for protection, yet they are safe in water, how?
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उत्तर
Frog’s eggs are without any external covering or shell but a layer of jelly hold the eggs together, thus providing them protection.
This jelly or gelatinous covering also protects them from drying up and prevents them from being eaten up by other animals or predators.
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संबंधित प्रश्न
State whether the following statement is true (T) or false (F):
The plumule of an embryo gives rise to the root system.
Define the Zygote.
Suppose a normal woman has never borne a child; How many mature eggs would she have produced in her lifetime? Your calculation should be based on two clues-
(a) Eggs are produced at the rate of 1 egg every 28 days (one menstrual cycle)
(b) A woman’s total reproductive period is 13 – 45 years.
Given below is a portion of the diagram to show the diagrammatic highly magnified view of a single human sperm. Complete the diagram to show its normal structure.
Name the female sex hormones and structures which secrete them.
Give Reasons
The urethra is also called urinogenital duct.
Study the diagram given below and then answer the questions that follow:
(i) Name the part labeled A. Name any two hormones produced by the part labeled A.
(ii) What happens to the part labeled B.
(1) if fertilization takes place?
(2) If fertilization does not take place?
(iii) Where does fertilization occur?
(iv) Draw a neat diagram of the human sperm as seen under high magnification and label the following parts.
(1) Acrosome
(2) Mitochondria
Give Technical Term:
In how many weeks fetus development is completed?
Give Technical Term:
A method of contraception in which the sperm duct is cut and ligated.
What are the functions of each hormone in the neurohypophyseal hormone?
