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GCSE Biology B2 > Inheritance and Genetics > Flashcards

Inheritance and Genetics Flashcards

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1
Q

Why are new cells needed in an organism? (3)

A

Growth, replacing worn out cells, repairing damaged tissue

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2
Q

Define allele?

A

Different form of the same gene

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3
Q

Define gene?

A

A section of DNA that codes for a particular combination of amino acids which make a specific protein

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4
Q

Define chromosome?

A

Genes grouped together

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5
Q

Define mitosis?

A

Cell division in a normal body cell, produces two identical cells

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6
Q

How does mitosis work?

A

Cell produces copies of the chromosomes in the nucleus, then divides once

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7
Q

Define stem cell?

A

Unspecialised and undifferentiated cell found in early embryos

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8
Q

Difference between animals and plants in terms of cellular differentiation?

A

Animals - differentiation only occurs in embryonic stage, so stops at maturity. Plants - cells don’t differentiate until they are in their final position in the plant, impermanent, can redifferentiate

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9
Q

Why is animal cloning more difficult than plant cloning?

A

Animal cloning - cells differentiate permanently. Plants - undifferentiated cells always produce more

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10
Q

What happens in meiosis?

A

Cell copies chromosomes so there are four sets, then divides twice in quick succession to form four gametes

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11
Q

Why is each gamete produced in meiosis different from the others?

A

They contain random mixtures of the original chromosomal pairs. Introduces variety

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12
Q

How is variation produced in sexual reproduction?

A

The combination of genes in the new pair of chromosomes contains alleles from each parent. One gamete from one parent will be different to another from the same.

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13
Q

How to remember mitosis and meiosis?

A

MITosis - Making Identical Two

MEiosis - Making Eggs (and sperm)

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14
Q

Difference between gametes and body cells?

A

Body cells have two sets of chromosomes; gametes only one

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15
Q

Describe the process of stem cell manufacture?

A

Stem cells removed from early embryo and cultured/cultivated. Stem cells differentiate into different tissues, then are implanted into a body.

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16
Q

Other than an embryo, where might stem cells be found?

A

Bone marrow, also in different tissues in the body; umbilical chords

17
Q

Problems with stem cells?

A

Ethical (embryos can’t give permission, taking human life); may cause cancer

18
Q

What does therapeutic cloning involve?

A

Using cells from an adult to proceed a cloned early embryo of themselves

19
Q

Why didn’t people believe Mendel’s findings?

A

They didn’t understand genes or chromosomes

20
Q

How is DNA composed?

A

Combinations of four different bases (ACTG) make up the long strands, grouped in threes, with each three coding for an amino acid

21
Q

Define homozygous

A

An individual with two identical alleles for a characteristic e.g. DD or dd

22
Q

Define heterozygous

A

An individual with different alleles for a characteristic, e.g. Dd

23
Q

Define genotype

A

Describes the genetic makeup of an individual regarding a particular characteristic, e.g. DD or Dd

24
Q

Define phenotype

A

The physical appearance of an individual regarding a particular characteristic, e.g. dimples or no dimples

25
Q

Difference between dominant and recessive alleles?

A

Dominant controls the development of a characteristic when one or both chromosomes have it (one or both parents). Recessive only controls such if it is present in BOTH chromosomes (i.e. both parents)

26
Q

Which gender does an XX sex chromosome determine?

A

Female (male is XY)

27
Q

What is polydactyly?

A

A genetic condition where a baby is born with extra fingers or toes, caused by a dominant allele

28
Q

What are the symptoms of cystic fibrosis? Is it caused by a dominant or recessive allele?

A

Organs are clogged by thick, sticky mucus and the reproductive system is affected, making the individual infertile in some cases

29
Q

Define a carrier (of cystic fibrosis)?

A

Someone who has a dominant healthy allele, but also a recessive cystic fibrosis allele. They have no symptoms, but their children have a 25% chance of getting it

30
Q

What are the chances of a child have polydactyly if a parent is heterozygous? And homozygous?

A

Heterozygous: 50% (half the gametes contain a faulty allele)
Homozygous: 100%

GCSE Biology B2 (9 decks)

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