3.7.1 Inheritance Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 2) > 3.7.1 Inheritance > Flashcards

Flashcards in 3.7.1 Inheritance Deck (63)
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1

What is a genotype?

The genetic make up on an organism. It describes ALL the alleles that an organism has.

2

What is an allele?

A different version of the same gene

3

What is a gene?

Short section of DNA made up of nucleotide bases, which codes for a specific order of amino acids which makes a protein.

4

What is a phenotype?

Observable characteristics due to environment and genetic makeup

5

What is a homologous pair?

A pair of chromosomes - maternal and paternal. Also known as a bivalent

6

What is a recessive allele?

An allele whereby you need 2 copies of it (homozygous) to express that characteristic. Its not expressed if the dominant allele is present.

7

What is a dominant allele?

You only need ONE copy of this allele to express this characterisitic

8

Homozygous dominant means?

Two dominant alleles present (in the genotype)

9

Homozygous recessive means?

Two recessive alleles present (in the genotype)

10

Heterozygous means?

One recessive and one dominant allele present (in the genotype)

11

A codominant allele is?

Where both alleles contribute/expressed in the phenotype

12

What are multiple alleles?

Where you have more than two alleles for a particular gene

13

In a diploid organism (human) how many chromosome pairs are there?

23

14

In meiosis what happens to the diploid number?

It becomes haploid - halves

15

Characteristics are determined by your allele combinations, how many alleles for each characteristics end up in the gamete?

1

16

Pure breeding plants are said to be

Homozygous

17

If there are 30 boys and 15 girls what is the ratio?

2:1

18

Why are actual ratios not exactly the same as theoretical ratios in genetics?

Because fertilisation of gametes occurs by chance - each time a gamete is fertilised, it is an independent event of what has gone before it.

19

How can you try and get theoretical ratios to match observed/actual ratios?

Increase sample size so its more representative

20

If you were to perform a statistical test on Mendelian genetics and you where looking at observed and expected ratios - what test would you do and why?

Chi Squared - because you are comparing observed and expected values and determining if there is a statistical difference

21

Suppose you obtained a chi squared value of 5 and the critical value was 5.99 (2dof) - what can you conclude?

Because the chi squared value is SMALLER than the critical value - you accept the null hypothesis and there is greater than a 5% probability that the difference in the results are due to chance. There is no significant difference.

22

Suppose you obtained a chi squared value of 8 and the critical value was 5.99 (2dof) - what can you conclude?

Because the chi squared value is LARGER than the critical value - you reject the null hypothesis and there is less than a 5% probability that the difference in the results are due to chance. There is a significant difference.

23

What is the difference between monohybrid inheritance and dihybrid inheritance?

Monohybrid is the inheritance of a SINGLE gene, dihybrid is the inheritance of TWO genes (that are located on different chromosomes)

24

Give an examples of a characteristic that involves multiple alleles

Blood groups - IA, IB and IO

25

Identify the chromosomes that determine sex

Sex Chromosomes - X and Y

26

Female sex chromosomes are

XX

27

Male Sex Chromosomes are

XY

28

Which sex determines the sex of the child?

Males - as females always pass on a X in their gametes.

29

What are the criteria must be met to perform a chi squared test?

sample size is large (20+), data falls into catergories (green, yellow), compare experimental observations with theoretical ones (expected)

30

When performing a statistical test what must you always state before you carry the test out?

Null hypothesis - this states that there is 'no significant difference'....