B1h - variation and inheritance Flashcards Preview

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Flashcards in B1h - variation and inheritance Deck (13):
1

What does dominant and recessive characteristics depend on(3)

Dominant and recessive alleles

Dominant alleles are those expressed if present

Recessive alleles are those only expressed if the dominant allele is absent

2

What is homozygous

2 identical alleles

3

What is heterozygous

2 different alleles

4

What is genotype

The genetic makeup

5

What is phenotype

The characteristics expressed

6

How many chromosomes do most body cells contain(2)

23 matched pairs(for humans)

Different for different species

7

What are alleles

Different versions of the same gene

8

How is sex determined in mammals

By sex chromosomes(XX for female and XY for male)

9

How is there an equal chance of the offspring being male or female(3)(practice genetic diagrams)

A sperm will carry either an X or a Y chromosome

All eggs will carry an X chromosome

There is a random chance of which sperm fertilises an egg, so the sperm has an equal chance of containing an X or a Y chromosome

10

What causes genetic variation(3)

Mutations(random changes in genes or chromosomes)

Rearrangement of genes during the formation of gametes

The random nature of fertilisation resulting in a zygote with alleles from the father and mother

11

What are inherited disorders are caused by(2)

Faulty genes
-most of which are recessive

12

What issues can be raised by knowledge of inherited disorders in a family(2)

Whether to have children or not

Whether to abort an affected foetus

13

Use genetic diagrams to predict the probabilities of
inherited disorders passing to the next generation(no answer)

practice