Variation Flashcards

1
Q

What are inherited features?

A

Characteristics of an organism that are determined by their genes

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2
Q

What are acquired features?

A

Characteristics of an organism that determined by their environment

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3
Q

Inherited features can be discontinuous/discrete or continuous. What is the difference?

A

Discontinuous/discrete features have a limited range of phenotype possibilities but continuous features have a wide range of phenotype possibilities

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4
Q

Does asexual or sexual reproduction create variation?

A

Sexual

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5
Q

Why would a species want to reproduce asexually?

A

It is quicker to have offspring because the parent doesn’t need find a mater
If the parent is successful within their environment, it is good for the offspring to be identical to them because they are more likely to be successful

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6
Q

Why would a species want to reproduce sexually?

A

Sexual reproduction creates genetically unique offspring. If the environment changes e.g. new disease, there is greater chance that some individuals might have the genetic makeup to survive and then reproduce

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7
Q

What type of cell division is involved in sexual reproduction?

A

Meiosis

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8
Q

What is the purpose of meiosis?

A

Type of cell division to create gametes/sex cells

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9
Q

Where does meiosis occur?

A

In sexual organs - testes in males and ovaries in females

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10
Q

What three processes that occur during meiosis create variation?

A

Segregation of alleles
Independent assortment
Crossing over/recombination

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11
Q

Explain how segregation of alleles creates variation

A

During meiosis, only one chromosome from each homologous pair is placed into each gamete. Therefore each gamete only receives one allele from each gene and therefore gametes have unique combinations of alleles which increases variation.

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12
Q

Explain how independent assortment creates variation

A

independent assortment is the random way different homologous pairs of chromosomes line up along the cell equator during meiosis. Since each gamete only contains one chromosome from each homologous pair, the gametes contain unique combinations of chromosomes and hence alleles which increases variation in the offspring..

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13
Q

Explain how crossing over/recombination creates variation

A

Crossing over is when parts of homologous chromosomes and the alleles they carry are exchanged. This creates unique allele combinations in the gametes and therefore the offspring which increases variation.

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14
Q

Why do each gamete e.g. sperm and an egg, are haploid - have only half the genetic information of one parent/one member from each homologous pair?

A

When the egg and sperm fuse during fertilisation is forms a diploid zygote - the chromosome number is restored and each chromosome exists as a homlogous pair. Because each gamete only provided half the genetic information from each parent, the offspring is genetically unique which increases variation.

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15
Q

What other process causes variation but doesn’t necessarily occur during meiosis?

A

Mutations

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16
Q

Explain how mutations create variation

A

Mutations are a change in the base sequence of DNA. This creates new alleles. This new bases sequence creates a new type of protein which creates a new phenotype hence increasing the variation in the species.

17
Q

What is a somatic mutation and why can it not be passed on to the offspring?

A

Mutation that occurs in body cells/somatic cells - not those in sexual organs involved in meiosis. Since they don’t create gametes, the mutation cannot be passed on.

18
Q

What are gametic mutations?

A

Mutations that occur in gametes and therefore can be passed on to the offspring

19
Q

Why might a gametic mutation in a parent not be visible in an offspring?

A

Might occur in a gamete not involved in fertilisation
Might produced a recessive allele that is masked in the phenotype by a dominant allele
Might code for the same amino acid as the sequence prior to the mutation so the protein still functions the same
Might change the protein’s structure but not alter its function