Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AQA A-Level Biology > Chapter 9 - Genetic Diversity And Adaptation > Flashcards

Chapter 9 - Genetic Diversity And Adaptation Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a gene mutation?

A

Any change to the quantity or the base sequence of the DNA of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a substitution mutation?

A

When one base is substituted for another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why are mutations bad?

A

The order of DNA bases in a gene determines the amino acid sequence which codes for a certain protein. If this is altered, it may lead to the protein lacking characteristics that are important for its role

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a deletion mutation?

A

One base is deleted from the DNA sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why do deletion mutations normally cause a large change to the organism?

A

Every base after the one that has been deleted experiences a frameshift and moves one to the left. Because bases are read in triplets, the codons aren’t read correctly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What will adding a base result in?

A

A frame-shift to the right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a silent mutation?

A

Because the DNA code is degenerate, a substitution mutation may result in the same amino acid being coded for and so have no effect on the organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a mutagenic agent?

A

Something that increases the likelihood of a mutation, e.g. UV radiation and ionising radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are chromosome mutations?

A

Spontaneous changes in the number of or structure of whole chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the two forms of chromosome mutations?

A

Changes in whole sets of chromosomes

Changes in the number of individual chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When will changes to whole sets of chromosomes occur?

A

When organisms have three or more sets of chromosomes rather than the normal two

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a change to a whole set of chromosomes called?

A

Polyploidy and it occurs mainly in plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is non-disjunction?

A

When homologous pairs of chromosomes fail to separate during meiosis. This leads to changes in the number of individual chromosomes and sometimes syndromes like Down’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What causes Down’s syndrome?

A

An extra copy of chromosome 21

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many daughter cells are produced from meiosis?

A

4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many divisions take place during meiosis?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a haploid number?

A

The number of chromosomes gametes have - half of the normal amount

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the diploid number?

A

The full set of 46 chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens during the first division of meiosis?

A

Homologous chromosomes pair up and their chromatids wrap around each other
One chromosome from each pair goes into one of the daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens during the second division of mitosis?

A

The centromere is divided and the sister chromatids move to each end of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a gene?

A

A length of DNA that codes for a polypeptide

22
Q

What is the locus?

A

The position of a gene on a chromosome or DNA molecule

23
Q

What is an allele?

A

Different forms of a gene

24
Q

What are homologous chromosomes?

A

One maternal and one paternal chromosome which have the same gene loci

25
Q

Are daughter cells genetically different in meiosis or mitosis?

A

Meiosis

26
Q

How many divisions are there in meiosis?

A

2

27
Q

What is the first division of meiosis?

A
  • arranged into homologous pairs (made up from one maternal/one paternal)
  • crossing over - chromatids twist and swap (known as ‘chriasmata’
  • same gene but different combination of alleles
  • GENETIC VARIATION
28
Q

What is the second division of meiosis?

A
  • pairs of sister chromatids separate - halving the number (HAPLOID)
  • random which chromosome ends in which daughter cell
  • different combination
  • GENETIC VARIATION
29
Q

What is the formula for the possible number of chromosomes in each daughter cell?

A

2^n

N=number of homologous chromosomes

30
Q

What is the formula for the number of chromosomes in each daughter cell, taking into account the random pairing of gametes?

A

(2^n)^2

31
Q

What is independent segregation?

A

Happens in the second division of meiosis. It’s where the chromosomes randomly end up in each daughter cell which means that the daughter cells have a completely different combination of maternal and paternal genes

32
Q

What is crossing over of chromatids?

A

This happens during the first division of meiosis. Chromatids twist. where the parts of the chromatids are twisted swap they with each due to the tension built up from twisting.

33
Q

What is chiasmata?

A

Where the two points was chromatids break apart

34
Q

What is a gene?

A

A length of DNA that codes for a polypeptide

35
Q

What is a locus?

A

The position of a gene on a chromosome or DNA molecule

36
Q

What is the allele?

A

One of the different forms of particular genes

37
Q

What is a homologous chromosomes?

A

A pair of chromosomes, one maternal and one paternal, that have the same gene loci

38
Q

What is genetic diversity?

A

The total number of different alleles in the population

39
Q

What is a population?

A

A group of individuals of the same species that live in the same place and can interbreed

40
Q

How are species diversity reduced?

A

When a species have fewer different alleles

41
Q

Finish the sentence:

The greater the genetic diversity, …………..

A

The more likely that some individuals in a population will survive an environmental change

42
Q

Process of natural selection

A
  • within any population of a species there will be a gene pool containing a wide variety of alleles
  • randomly taken this may result in a new allele which in most cases it will be harmful
  • in certain environments, the new allele might give its possessor an advantage
  • these individuals will be better adapted and therefore more likely to survive in the competition with others
  • these individuals will grow move rapidly and live longer, due to this they will have a better chance of breading successfully and producing more offsprings
  • only individuals that reproduce successfully will pass on the allele to the next generation
  • as the new individuals also have the new advantageous allele, they are more likely to survive and so reproduce successfully
43
Q

What are the types of selection?

A
  • directional selection
  • stabilising selection
  • disruptive selection
44
Q

What is directional selection?

A

The population mean moves to the extreme in one direction changing the characteristics of the population.

45
Q

What is a stabilising selection?

A

Selection may favour average individuals meaning it preserves the characteristics of the population

46
Q

What is a disruptive selection?

A

Population will have two extremes have a large groups which become two different species

47
Q

How does directional selection work, for example in bacteria?

A

A spontaneous mutation will occur in the alleles of a gene in a bacteria that enables it to make a new protein. The new protein was an enzyme that breaks down the antibiotic before it was able to kill the bacteria. The bacterium happened by chance to be in a situation where the antibiotic had been used to treat an individual before.The bacteria that survive will be able to divide by binary fusion to build up a small population of ‘antibiotic’-resistant bacteria. This will increase the population of the non-resistant meaning the population is normal distribution curve shifted in the direction of a population having greater resistance to the bacteria this will increase the population of the non-resistant meaning the populations normal distribution curve shifted in the direction of a population having greater resistance to the bacteria

48
Q

How does stabilising selection work, for example, with babies’ birth weights?

A

When the babies birth weight is below 2.5 kg or above 4.0 kg there is a greater risk of infant death. Whilst those around the mean are less likely to die therefore the populations characteristics of preserved rather than changed.

49
Q

What are the three types of adaptations?

A
  • anatomical
  • physiological
  • behavioural
50
Q

What is an anatomical adaption? Give an example

A

Changing the physical structure of the body.

Foxes in the arctic have shorter ears and thick fur

51
Q

What is a physiological adaption? And give an example

A

Chemical reactions in the body. For example, Oxidising of fat rather than carbohydrate in kangaroo rats to reduce additional water in a dry desert environment

52
Q

What is a behavioural adaptation? Give an example.

A

The way an animal acts. Autumn migration of swallows from the UK to Africa to avoid food storages in the UK winter

AQA A-Level Biology (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions