6.1.8 - sex determination Flashcards
(8 cards)
1
Q
How many pairs of chromosomes in ordinary human body cells?
A
23
2
Q
What do 22 of the pairs of chromosomes in a human body cell do?
A
Control characteristics only.
3
Q
What does only one of the pairs of chromosomes in a human body cell do?
A
carries the genes that determine sex
4
Q
What are the female sex chromosomes?
A
XX
5
Q
What are the male sex chromosomes?
A
XY
6
Q
Egg cell and sperm cell chromosomes - X or Y?
A
Egg cells always carry an X chromosome
Sperm cells can carry an X or a Y chromosome
7
Q
Probability of boy or girl at each pregnancy as a ratio
A
50:50 or 1:1
8
Q
Draw punnett square to show possible combination of gametes
A
X X
X XX XX
Y XY XY
(label which shows the female gametes and which shows the male ones - row = female, column = male)
