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Question 1

1. What formation of chromosomes do body cells and sex cells have?

Answer 1

Body cells contain pairs of chromosomes (one from each pair from each parent)
Sex cells contain only one chromosome from each pair

Question 2

1. How many chromosomes does a human body cell and sex cell have?

Answer 2

Human body cell- 23 pairs, 46 in total

Human sex cell- 23 single chromosomes

Question 3

2. Where are the genes in each chromosome pair positioned?

Answer 3

In the same place

Question 4

2. What is an allele?

Answer 4

Different versions of the same gene

Question 5

3. How many alleles per gene does an individual usually have?

Answer 5

two alleles for each gene

Question 6

4. What is it called when in an individual the two alleles of each gene can be the same, and when they are different?

Answer 6

Same- homozygous

Different- heterozygous

Question 7

5. What happens in sexual reproduction?

Answer 7

genes from both parents’ sex cells come together and produce variation in the offspring; the fertilised egg then has 23 pairs of chromosomes like a normal body cell.

Question 8

6. Why do the offspring have some similarities to both of their parents?

Answer 8

Offspring have some similarities to their parents because of the combination of both maternal (from their mam) and paternal (from their dad) alleles in the fertilised egg

Question 9

7. Why do offspring from the parent not look exactly the same?

Answer 9

-because they inherit a different combination of maternal and paternal alleles

Question 10

8. What two things can an allele be? How are these shown in genetic diagrams?

Answer 10

• dominant (shown as capital letters)

- recessive (shown as lowercase letters)

Question 11

8. What characteristic will be shown with one dominant and one recessive allele? (Aa)

Answer 11

Will show the associated dominant characteristic

Will not show the associated recessive characteristic, as the dominant masks this characteristic

Question 12

8. What characteristic will be shown with two dominant alleles? (AA)

Answer 12

Will show the associated dominant characteristic

Question 13

8. What characteristic will be shown with two recessive alleles? (aa)

Answer 13

Will show the associated recessive characteristic

Question 14

9. What sex chromosomes do male and females have?

Answer 14

Male: XY
Female: XX

Question 15

10. How does one become a male?

Answer 15

-The sex-determining gene on the Y chromosome produces a protein that triggers the development of testes which then produces male sex hormones and the rest of the male reproductive system

Question 16

10. How does one become female?

Answer 16

-In the absence of a Y chromosome this protein is not produced and the ovaries develop, then the rest of the female reproductive system

Question 17

12. What do the terms genotype and phenotype mean?

Answer 17

Genotype: the genetic make-up of an organism (the combination of alleles)
Phenotype: the observable characteristics that the organism has