(a) Describe briefly the female reproductive system of a named mammal. (A diagram is essential). (b) List three differences between reproduction in mammals ...

(a) Female reproductive system of a named mammal (woman/human, diagram essential)

The labelled diagram (front view) should show and label:

• Two ovaries: almond-shaped organs that produce the ova (eggs) and secrete the hormones oestrogen and progesterone.
• Two oviducts (fallopian tubes): tubes with funnel-shaped, fringed openings (fimbriae) that receive the ovum and carry it towards the uterus; fertilisation takes place here.
• Uterus (womb): a muscular, pear-shaped organ with a soft inner lining (endometrium) in which the fertilised egg implants and the foetus develops.
• Cervix: the narrow neck of the uterus that opens into the vagina.
• Vagina: the muscular tube that receives the penis during mating and serves as the birth canal.

In brief, the ovaries release an ovum at ovulation; it passes into the oviduct where, if sperm are present, fertilisation occurs; the resulting zygote travels to the uterus, implants in its lining and develops into a foetus until birth.

(b) Three differences between reproduction in mammals and in amphibians

(c) Structure and function of the male reproductive organ of a flowering plant (the stamen)

The male reproductive organ is the stamen (androecium). Each stamen is made up of two parts:

• The anther: a two-lobed structure containing four pollen sacs. Inside these sacs the pollen grains are formed. The anther produces and stores the pollen grains, which carry the male gametes, and splits open (dehisces) at maturity to release them for pollination.
• The filament: the stalk that bears the anther. It holds up and supports the anther in a suitable position to expose the pollen for dispersal, and supplies it with water and nutrients through its vascular tissue.

Each mature pollen grain contains a generative nucleus (which divides to form two male gametes) and a tube nucleus (which controls the growth of the pollen tube during fertilisation). Thus the stamen's function is to produce the male gametes and make them available for pollination and fertilisation.