Q1 Fig. Shows Stages in the Formation of a Human Fetus

CHOITHRAM INTERNATIONAL WORK SHEET BIOLOGY

Q1 Fig. shows stages in the formation of a human fetus.

(a) (i) Name the process of cell division that results in the formation of sperm cells.

(ii) State one way in which the sperm cell is different from cells in the developing fetus.

(iii) State the term used to describe the fertilised egg cell.

(iv) Explain what determines that a fertilised egg cell develops into a girl rather than a boy.

(b) State where each of the following is produced. (i) the egg cell (ii) the fertilised egg (iii) the fetus

(c) The fetus is surrounded by amniotic fluid and an amniotic sac. State their functions.

(d) (i) Outline the role of the placenta in the development of the fetus.

(ii) Describe the role of the placenta in maintaining pregnancy.

Q2 (a) Using straight lines, match the names of the flower parts with their functions. One has been completed for you.

(b) Describe how the stigmas of wind- pollinated flowers differ from the stigmas of insect pollinated flowers. Relate these differences to the use of wind as the pollinating agent.

(c) Discuss the implications to a species of self- pollination.

Q3 Pollen grains start to germinate when they land on a suitable stigma and produce a pollen tube. Fig. shows a single carpel from a flower with a germinating pollen grain.

(a) (i) Identify the structures labelled A, B and C (b) (ii) Draw a line on Fig. to continue the path taken by the pollen tube until it enters structure C.

(b) (i) Measure the diameter of the pollen grain shown in Fig. and the approximate distance the pollen tube grows to reach and enter structure C. Diameter of pollen grain mm Distance grown mm (ii) How many times greater is the distance grown by

the pollen tube than the diameter of the pollen grain? Fig.

Q4 Fig. shows a side view of the female reproductive system. Fig. (a) Using label lines and the letters given, label the following on Fig. . S. where the penis is inserted during sexual intercourse D. where a diaphragm (cap) would be placed to prevent pregnancy M. where an ovum matures F. where an ovum would be fertilised E. where an embryo would become implanted (b) Explain how (i) the ovum passes down to the uterus,

(ii) the structure of a sperm enables it to reach the ovum,

(iii) a zygote has a diploid number of chromosomes, (iv) the level of a hormone which prevents menstruation remains high during pregnancy, even after the corpus luteum has broken down.

Q5 [o/n 07] Fig. shows a diagram of a section through the male reproductive organs. Fig. (a) Complete the table by using the labels from Fig. to identify each of the structures described. The first has been done for you.

description of structure label letter carries both urine and semen D where sperm are stored before ejaculation is cut or tied during a vasectomy produces fluid for sperm to swim in where meiosis occurs First variant Question Pape (b) In older men the prostate gland often enlarges, reducing the diameter of tube D. (i) State the name of tube D. (ii) Suggest and explain why a reduction in the diameter of this tube may cause a problem.

(c) Some processes in the body involve the deliberate narrowing of structures. Outline one situation in the body where there is a mechanism to reduce the diameter of a structure for a particular purpose. State the effect of this reduction in diameter.

First variant Question Pap (d) Hormones can be used as a birth control mechanism and also to increase fertility. Describe the use of named hormones in 1. fertility drugs, 2. chemical methods of birth control. Q6 Nov 2004 State the sites of production and describe the roles of oestrogen and progesterone (i) in the menstrual cycle; [6] (ii) during pregnancy. [4]

Q7 Nov 2002(i) Outline the implications to a species of self-pollination. [3] (ii) Describe the features that make a typical wind-pollinated flower different from a typical insect-pollinated flower. [9] (iii) Suggest how pollen of a wind-pollinated flower would be different from that of an insectpollinated flower. [3]

Q 8 MJ 03 (a) State the functions of five named parts of the male reproductive system. [5] (b) (i) Explain how sperm, deposited in the vagina during sexual intercourse, reach an egg. [4] (ii) Describe the process of fertilisation. [3] (c) Outline the ways in which HIV can be prevented from spreading. [3] [Total : 15]