1 Fig. 1.1 shows the reproductive system of a female farm animal. (a) Name the structures labelled X, Y and Z in Fig. 1.1. [3] (b) State the function of the...

Labelled answer diagram:

(a) Structures labelled X, Y, and Z [3]

1. X - Ovary: the paired organs that produce egg cells (ova) and the reproductive hormones oestrogen and progesterone. [1]
2. Y - Oviduct (fallopian tube): the narrow tube that carries the released egg from the ovary toward the uterus. Fertilisation normally takes place in the upper part of the oviduct. [1]
3. Z - Uterus (womb): the muscular organ where the fertilised egg implants and the embryo develops throughout pregnancy. [1]

(b) Function of structure Y (oviduct) [1]

The oviduct carries the egg from the ovary to the uterus by means of muscular contractions and the beating of cilia that line its inner surface. It is also the site where fertilisation occurs - sperm travelling up the reproductive tract meet and fuse with the egg in the oviduct. [1]

(c) What happens to the uterine lining if the egg is not fertilised [2]

1. If fertilisation does not occur, the corpus luteum on the ovary degenerates and progesterone levels fall. Without progesterone to maintain it, the thickened lining of the uterus breaks down. [1]
2. The lining is shed, and the animal returns to oestrus (heat), restarting the reproductive cycle. [1] In farm animals this is a cyclical process (the oestrous cycle), not menstruation as in humans - the lining is largely reabsorbed rather than discharged as blood.

(d) Two reasons for keeping accurate breeding cycle records [2]

Any two of:

1. To predict when the animal will be in heat (oestrus) so the farmer can plan mating or arrange artificial insemination at the optimal time for conception. [1]
2. To estimate the expected date of birth (parturition) so the farmer can prepare appropriate care, housing, and veterinary support for the pregnant animal. [1]
3. To identify animals that are not cycling regularly, which may indicate health problems requiring veterinary attention.
4. To plan the timing of breeding to ensure calving, lambing, or kidding occurs at the most favourable time of year.