Topic 3: Gametes

Question 1

Most body cells are ________.

Gametes (e.g. sperm, ovum) are ________.

Answer 1

diploid

haploid

Question 2

Define diploid (1 point)

Answer 2

1. the {full number/complement} of chromosomes found in all {somatic cells/body cells except gametes}
   e. g. 46 in humans

Question 3

Define haploid (1 point)

Answer 3

1. when cells have half the number of chromosomes of {body/somatic} cells

Question 4

What are the functions of the ovum being large? (2 points)

Answer 4

1. Many sperm able to fit round it, so INCREASED CHANCE OF FERTILISATION
2. Contains MORE lipid droplets, so more energy for developing embryo

Question 5

What is the function of the zona pellucida? (1 point)

Answer 5

1. {Thickens/hardens} when one sperm has entered to stop further sperm entering (prevents polyspermy)

Question 6

What is the function of lysosomes in the ovum? (1 point)

Answer 6

1. Release ENZYMES CAUSING ZONA PELLUCIDA TO THICKEN to prevent polyspermy - more than one sperm entering the ovum

Question 7

What is the purpose of cytoplasm with proteins & lipids in the ovum? (1 point)

Answer 7

1. Proteins and lipids are a FOOD SOURCE TO SUPPLY {ENERGY/nutrients} FOR CELL DIVISION

Question 8

Why do gametes have a haploid nucleus? (2 points)

Answer 8

1 (this point is important). Contain half the number of chromosomes, so that the diploid chromosome number is restored at fertilisation.

2. Mixing of alleles allows for GENETIC VARIATION

Question 9

What is the purpose of receptors on the ovum surface? (1 point)

Answer 9

1. Allow sperm to bind

Question 10

What is the function of the sperm being small? (1 point)

Answer 10

1. To enable sperm to move easily.

Question 11

What is the function of a flagellum in a sperm? (1 point)

Answer 11

1. Allows SPERM TO SWIM TO REACH THE OVUM in the oviduct.

Question 12

Why do sperm have a large number of mitochondria? (1 point)

Answer 12

1. Carry out AEROBIC RESPIRATION to {release/provide} ATP for energy for moving the tail so that sperm can swim to egg

Question 13

What is the function of the acrosome containing enzymes? (1 point)

Answer 13

1. Specialised lysosome which contain and release DIGESTIVE ENZYMES, WHICH HYDROLYSE THE ZONA PELLUCIDA enabling sperm to enter the ovum

Question 14

What is the purpose of the sperm having a streamlined shape? (1 point)

Answer 14

1. Reduces resistance when swimming to ovum

Question 15

What is the purpose of the receptors in cell membrane of a sperm? (2 points)

Answer 15

1. Bind to egg cell surface membrane

2. detect chemicals released by ovum

Question 16

What are the SIMILARITIES between the sperm and the ovum?

3 points

Answer 16

Both have:

1. cell membrane,
2. cytoplasm,
3. mitochondria

Question 17

What are the DIFFERENCES between the sperm and the ovum?

3 points

Answer 17

1. Sperm have an acrosome, the ovum does not
2. Sperm have a flagellum, the ovum does not
3. Ovum has a zona pellucida, the sperm does not