Biology
Given below is a diagram of the lateral section of a testis of a man. Study the same and answer the questions that follow:
(i) Label the parts numbered 1 to 4 of the diagram.
(ii) State the functions of the parts labelled 1 and 3.
(iii) What is the significance of the testes being located in the scrotal sac outside the abdomen?
(iv) What is the role played by the inguinal canal?
(v) What is semen?
Answer
(i) The parts numbered 1 to 4 of the diagram are:
- 1 → Seminiferous tubules.
- 2 → Testicular lobes
- 3 → Epididymis
- 4 → Sperm duct/Vas deferens.
(ii) The functions of the parts labelled 1 and 3 are:
- Part 1 (Seminiferous tubules): Seminiferous tubules produce sperms by the process called spermatogenesis.
- Part 3 (Epididymis): The epididymis stores the sperms for some days for maturation and transport it to vas deferens.
(iii) Testes are responsible for the production of male gametes i.e. sperms. The normal body temperature does not allow for the maturation of the sperms. Being suspended outside the body cavity, the temperature in the scrotal sac is 2 to 3°C lower than that of the body which is the suitable temperature for the maturation of the sperms.
When it is too hot, the skin of the scrotum loosens so that the testes hang down away from the body. When it is too cold, the skin contracts in a folded manner and draws the testes closer to the body for warmth.
(iv) Inguinal canal allows the descent of testes along with their ducts, blood vessels and nerves, etc. The sperm duct from each Testis travels upwards into the abdomen passing through the Inguinal canal.
(v) Semen is the mixture of sperms and secretions from seminal vesicles, prostrate and cowper's glands. It is a milky fluid.
Related Questions
Draw a diagram of the human eye as seen in a vertical section and label the parts which suits the following descriptions relating to the:
(i) photosensitive layer of the eye.
(ii) strucutre which is responsible for holding the eye lens in its position.
(iii) structure which maintains the shape of the eye ball and the area of no vision.
(iv) anterior chamber seen in front of the eye lens.
(v) outer most transparent layer seen in front of the eye ball.
Give the biological/technical terms for the following :
(i) Chemical found in the blood which act against antigens.
(ii) A constituent that causes pollution.
(iii) The onset of menstruation in a young girl.
(iv) Structure which connects the placenta with the foetus.
(v) The fluid present between the layers of meninges.
(vi) Permanently open structures seen on the bark of an old woody stem.
(vii) The biological process which is the starting point of the food chain.
(viii) The change in an organism resulting due to stimulus.
(ix) An Antiseptic substance present in tears.
(x) A solution in which the relative concentration of water molecules and the solute on either side of the cell membrane is the same.
Differentiate between the following pairs on the basis of what is mentioned in brackets :
(i) Photolysis and Photophosphorylation. (Definition)
(ii) Bicuspid valve and Tricuspid valve. (Function).
(iii) Vasectomy and Tubectomy. (Explain)
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(v) Bowman's capsule and Malpighian capsule. (Parts included)
Given below is a schematic diagram showing Mendel's Experiment on sweet pea plants having axial flowers with round seeds (AARR) and Terminal flowers with wrinkled seeds (aarr). Study the same and answer the questions that follow:
(i) Give the phenotype of F1 progeny.
(ii) Give the phenotypes of F2 progeny produced upon by the self-pollination of progeny.
(iii) Give the phenotypic ratio of F2 progeny.
(iv) Name and explain the law induced by Mendel on the basis of the above observation.