Fig. 6.1 shows the human male reproductive system as seen from the side. Sperm cells are produced continuously in the testes from the time a boy reaches pub...
Question 1 Report
Fig. 6.1 shows the human male reproductive system as seen from the side. Sperm cells are produced continuously in the testes from the time a boy reaches puberty. The sperm cells then pass along a series of tubes, mixing with fluids released by several glands to form semen, before they leave the body. The letters P, Q, R and S label four structures involved in the production and release of sperm cells.
(a) Using Fig. 6.1, name the structure labelled P in which the sperm cells are made. [1]
(b) State the letter, from Fig. 6.1, of the tube along which sperm cells pass on their way out of the body. [1]
(c) Describe two ways in which the testes are adapted for the continuous production of large numbers of sperm cells. [2]
(d) Explain why sperm cells need the sugary fluid that is added to them by the glands to form semen. [3]
(e) Explain the advantages to a species of producing offspring by sexual reproduction rather than by asexual reproduction. [3]
Answer Details
This question refers to Fig. 6.1, a side view of the male reproductive system with structures labelled P, Q, R and S; the answers below follow the standard anatomy of that system.
(a) Structure P, where the sperm cells are made, is the testis (testes) [1]. Sperm are produced continuously in the seminiferous tubules of the testis from puberty.
(b) The tube along which sperm pass on their way out of the body is S (the sperm duct leading to the urethra) [1].
(c) Two adaptations of the testes for continuous production of large numbers of sperm (1 each): they contain many coiled seminiferous tubules, giving a large surface area for sperm production [1]; and they are held outside the body in the scrotum, at a slightly lower temperature that is best suited to sperm production [1].
(d) Sperm need the sugary fluid because the sugar (fructose) provides energy for respiration [1]; this respiration takes place in the many mitochondria in the middle piece of the sperm [1]; the energy released is used to move the tail (flagellum) so the sperm can swim to the egg [1].
(e) The advantage of sexual over asexual reproduction is that it produces genetic variation in the offspring [1], because genes come from two parents when gametes fuse at fertilisation [1]; this variation means the species is more likely to have some individuals that survive a change in the environment or a new disease [1].
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