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?
(a) Tissue culture is the technique that has helped scientists propagate the desired crops on a large scale in a short duration. The following steps are carried out to propagate crops by tissue culture:
i) Tissue culture is the process of developing a complete plant from a part of a plant. The plant part is called an explant.
ii) Explants can be grown in sterile conditions in special nutrient media to regenerate complete plants.
iii) Nutrient media contain a carbon source (such as sucrose), organic salts, vitamins, amino acids and phytohormones.
iv) Hence, propagation is achieved for a large number of plants in a short duration. This process is called micro propagation.
v) All the plants obtained by tissue culture are called somaclones since they are genetically identical to each other as well as the parent plant.
(b) Somatic hybrids are obtained by the method of somatic hybridisation. In this method, the somatic parts of two plants are hybridised. Protoplasts are isolated and fused to get a hybrid protoplast that grows further to form a new plant. For example, protoplasts of potato and tomato have been actually fused to form a pomato. But this plant is not commercially viable, as it does not have all the desired combination of characteristics for its commercial utilization
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?
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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