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Name the method by which spirogyra reproduces under favourable conditions. Is this method sexual or asexual?
What happens when :
Accidently, Planaria gets cut into many pieces?
When Planaria gets cut into many pieces, it will undergo regeneration process due to which each piece will grow into a new Planaria organism.
What happens when :
Bryophyllum leaf falls on the wet soil?
When Bryophyllum leaf falls on the wet soil, the buds that are produced in the notches along the leaf will develop into new plants by the process known as vegetative propagation.
What happens when :
On maturation sporangia of Rhizopus bursts?
State the changes that take place in the uterus when :
Implantation of the embryo has occurred.
When implantation of embryo has occurred the uterine wall thickens and is richly supplied with blood to nourish the growing embryo.
State the changes that take place in the uterus when :
Female gamete/egg is not fertilised
If the egg is not fertilised, it lives for about one day. Since the thickened uterus lining is no more required, it will slowly break down and comes out through the vagina as blood and mucous known as menstruation.
Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and writes its functions.
The organ that produces sperms, as well as secrets male hormone, is testis.
The function of testosterone is to control the development of male sex organs and secondary male features such as a deeper voice, moustache, beard and more body hair.
Name the parts of the human female reproductive system where fertilisation occurs.
Fertilisation takes place in the fallopian tubes.
Explain how the developing embryo gets nourishment inside the mother's body.
The foetus gets its nourishment from the special tissue called placenta. After implantation, a disc-like special tissue called placenta develops between the uterus wall and the embryo. The placenta helps in the exchange of nutrients, oxygen and waste products between the embryo and the mother. Thus, it provides nourishment to the growing embryo.
Name the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost. Write the first step from where such a type of reproduction begins. Draw first two stages of this reproduction.
Binary fission is the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost.
This reproduction starts with the division of nucleus (karyokinesis).
Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival - the one reproducing asexually or the one reproducing sexually ? Give a reason to justify your answer.
The difference between asexual and sexual reproduction is that in asexual reproduction only one parent is involved, whereas in the sexual mode of reproduction two parents are involved.
The organisms reproducing sexually have better chances of survival because it incorporates variations and promotes diversity of characters in an offspring due to combinations of genes and thus the offsprings are better adapted to the environment and therefore have better chances of survival.
(a) Write the function of following parts in the human female reproductive system :
(i) Ovary (ii) Oviduct (iii) Uterus
(b) (a) Write the function of following parts in the human female reproductive system :
(i) Ovary (ii) Oviduct (iii) Uterus
(b) Describe in brief the structure and function of the placenta
(a)
(i) The ovaries have two main reproductive functions in the body. They produce eggs for fertilization and they produce the reproductive hormones, oestrogen and progesterone.
(ii) Oviduct known as fallopian tube help transmission the ova from the ovary to the uterus and providing the necessary environment for fertilization and for initial development of the egg or zygote.
(iii) Uterus help in nurturing the fertilized ovum that develops into the fetus and holding it till the bady is mature enough for birth.
(b) Th placenta provides a large surface area for glucose and oxygen to pass from the mother to the embryo. The waste substances generated by the foetus is removed by transferring them into the mother’s blood through the placenta.
Name the process by which an amoeba reproduces. Draw the various stages of its reproduction in a proper sequence
Amoeba reproduces by binary fission. Amoeba splits into two daughter cells in any plane.
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