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Biology > Variation > Flashcards

Variation Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What type of variation occurs between individuals of the same species?

A

Intraspecific

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2
Q

What is the difference between continuous and discontinuous variation?

A

Continuous is controlled by a large number of genes, e.g. Height, hair colour.
Discontinuous is controlled by a small number of genes, e.g. Rolling your tounge, eye colour.

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3
Q

Does continuous variation or discontinuous variation tend to be qualitive?

A

Discontinuous.

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4
Q

How is continuous variation categorised?

A

Is it not categorised, there are no distinct categories.

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5
Q

True/false? Discontinuous variation is influenced by the environment.

A

False

Discontinuous variation is not influenced by the environment.

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6
Q

What is a phenotype?

A

A combination of alleles, when the gene is expressed, e.g. Proteins.

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7
Q

What environmental factors could affect the phenotype of a plant?

A
  • Light intensity
  • Competition
  • pH
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8
Q

What are some examples of animals who do courtship?

A

Peacocks, Lions (mane), Bower birds, Baboons.

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9
Q

Why is courtship done?

A

Enables potential mates to recognise their own species.
Avoids aggression between individuals.
Enables potential mates to synchronise their breeding behaviour.

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10
Q

Why causes a change in breeding behaviour causing the response of courtship to occur?

A

A stimulus from the environment, from a partner’s behaviour or from a hormone.

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11
Q

What differences do sexual selection cause?

A

Differences in appearance and behaviour between sexes

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12
Q

Why do animals often come into breeding in the spring?

A

Increased day length.

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13
Q

What section of DNA codes for a polypeptide?

A

A gene.

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14
Q

Why is a pair bond formed during courtship?

A

So the male and female can coordinate their behaviour.

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15
Q

Why are hybrid animals with an odd number of chromosomes infertile?

A

One chromosome won’t have a pair so meiosis cannot occur.

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16
Q

What is allele frequency the measure of?

A

Relative frequency of a allele on a genetic locus in a population.
Or it shows the genetic diversity of a species population or the richness of its gene pool.

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17
Q

What happens if a random allele mutation produces a beneficial allele?

A

The organism is more like to survive and breed successfully allowing them to pass on the beneficial allele to the next generation, which in turn will help them too.
The new allele will increase in frequency in the population over many generations.

18
Q

What is the Founder Effect?

A

When a small group migrates away or becomes isolated from a population. Inbreeding could potentially occur, however this small group may have a non-representing sample of alleles from the parent population so this new group may evolve different to the original, especially if the environment is different. (E.g. Birds of paradise)

19
Q

What is a mutation?

A

A change in the nucleotide sequence.

20
Q

Why is it dangerous if a mutation affects a large section of DNA?

A

Could mean a certain protein is not expressed

Would affect the tertiary shape of a protein molecule, so it would be able to function properly

21
Q

Give an example of how a mutation can be beneficial.

A

More efficient enzyme.

22
Q

What is base substitution in reference to mutation?

A

The replacement of one nucleotide with another containing a different base.

23
Q

What is deletion in relation to mutation?

A

The loss of a nucleotide.

24
Q

Why might a mutation have no effect?

A
  • It occurs in a non-coding region of the DNA.
  • A different codon may produce the same amino acid (so it’s degenerate)
  • The altered amino acid may not affect the protein’s shape or function.
25
Q

What is a mutagen?

A

Anything which causes causes a mutation.
Can be carcinogenic in higher organisms.
E.g. Ionising radiation
UV radiation

26
Q

What is non-dysfunction in relation to chromosome mutations?

A

The failure of homologous chromosomes or sister chromatids to separate properly during cell division.

27
Q

Give the definition of polyploidy.

A

Where an individual has sets of chromosomes greater than the normal diploid number.

28
Q

Give the definition of haploid.

A

When a cell has half the usual number of chromosomes.

29
Q

Give the definition of diploid.

A

A cell or organism that has paired chromosomes, one from each parent.

30
Q

Give the definition of triploid.

A

A cell containing 3 homologous sets of chromosomes.

31
Q

Give the definition of hybridisation.

A

The process of combining two complementary single-stranded DNA or RNA molecules and allowing them to form single-stranded molecule though base pairing to produce a hybrid.

32
Q

What happens during the 1st nuclear division of meiosis (meiosis 1)?

A

Homologous chromosomes pair up and their chromosomes wrap around each other, equivalent portions of the chromatids are exchange in crossing over.
At the end one chromosome from each pair goes into one of each of the 2 daughter cells.

33
Q

What occurs during the 2nd nuclear division of meiosis (meiosis 2)?

A

The chromatids move apart, at the end 4 cells have usually formed containing the haploid number of chromosomes.

34
Q

What is an allele?

A

One of the different forms of a particular gene.

35
Q

What are homologous chromosomes?

A

A pair of chromosomes, one maternal and one paternal, with the same genetics.

36
Q

What is independent segregation?

A

Each chromosome lines up alongside its homologous partner randomly, so one of each pair will pass to each daughter cell depending on how they’re lined up.

37
Q

What is crossing over?

A

During meiosis 1, each chromosome lines up alongside its homologous partner, they then twist around each other, however tensions are created and portions of the chromatids break off.
They then might rejoin with the chromatids of it’s partner. Usually equivalent portions are exchanged.

38
Q

What does crossing over create?

A

New genetic combinations of maternal and paternal alleles.

39
Q

Why might intraspecific variation occur?

A

If there is more offspring than the resources in a habitat can support, then there is intense intraspecific competition for resources.

40
Q

What resources might different species be competing for?

A

Finding food and mates.

Surviving disease and predators.

Biology (12 decks)

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