Short Answer TypeHow is 'oogenesis' markedly different from 'spermatogenesis' with respect to the growth till puberty in the humans?
Draw a sectional view of human ovary and label the different follicular stages, ovum and Corpus luteum.
Mention any three characteristics of Neanderthal man that lived in near east and central Asia.
Long Answer Type(a) Name the technology that has helped scientists to propagate on a large scale the desired crops in a short duration. List the steps carried out to propagate the crops by the said technique.
(b) How are somatic hybrids obtained?
Short Answer TypeLong Answer TypeDuring the reproductive cycle of a human female, when, where and how does a placenta develop? What is the function of placenta during pregnancy and embryo development?
During the reproductive cycle of human female, placenta develops after the implantation of zygote in the uterus.
After implantation, finger like projection called chorionic villi appear on the trophoblast. The chorionic villi are surrounded by uterine tissues and maternal blood. It is this chorionic villi and the uterine tissue which interdigitate with each other and jointly form a structural and functional unit between developing embryo and maternal body called placenta.
The functions of placenta are as follows:
1) Nutrition: It helps to transport nutrients from mother's blood to foetus for its development.
2) Respiration: It provides oxygen to the foetus and removes CO2 from the foetus.
3) Excretion: It helps in the removal of waste products from the foetus.
4) Immunity: It provides immunity to the foetus. Antibodies developed in mother's blood passes onto the foetus through the placenta.
5) Storage: It stores some fats, glycogen and iron.
6) Secretion of hormones: It secretes many hormones like oestrogen, progesterone, gonadotropin and placental lactogen that support the growth of the foetus.
Short Answer TypeDraw a diagram of the microscopic structure of human sperm. Label the following parts in it and write their functions.
(a) Acrosome
(b) Nucleus
(c) Middle piece
Long Answer Type(a) Draw a diagrammatic sectional view of the female reproductive system of human and label the parts:
(i) where the secondary oocytes develop
(ii) which helps in collection of ovum after ovulation
(iii) where fertilization occurs
(iv) where implantation of embryo occurs.
(b) Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females.Short Answer Type
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