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SHHS - Science - AQA Biology Trilogy > 4.6 Reproduction > Flashcards

4.6 Reproduction Flashcards

1
Q

A cell divides in a series of stages called

A

the cell cycle

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2
Q

What are the initial steps in the cell cycle?

A

The cell grows and organelle numbers increase, DNA replicates.

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3
Q

In the cell cycle after the DNA has replicated what happens next?

A

The copied chromosomes separate (mitosis) and then the cell divides into two.

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4
Q

What are the 2 forms of reproduction?

A

Asexual and sexual

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5
Q

Why is asexual reproduction important?

A

growth and repair

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6
Q

How many parents are involved in asexual reproduction?

A

1

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7
Q

How many parents are involved in sexual reproduction?

A

2

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8
Q

Which form of reproduction involves gametes?

A

sexual - fusion of egg and sperm

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9
Q

Which form of reproduction brings about variation?

A

sexual

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10
Q

Name an organism that reproduces asexually

A

bacteria, daffodil bulbs, strawberry tubers

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11
Q

Name an organism what reproduces sexually

A

humans

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12
Q

What form of cell division produces gametes?

A

Meiosis

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13
Q

Where does meiosis occur?

A

testes and ovaries

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14
Q

Where does mitosis occur?

A

in all body cells except testes and ovaries

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15
Q

In plants what are the sex cells?

A

pollen and egg cell

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16
Q

In animals what are the sex cells?

A

egg cell and sperm

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17
Q

What is another name for a gamete?

A

sex cell

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18
Q

Why does sexual reproduction bring about variation

A

Involves FUSION of egg and sperm, creating a unique combination of alleles

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19
Q

How many chromosome pairs are found in human body cells?

A

23 pairs

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20
Q

How many chromosomes are found in human sex cells

A

23

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21
Q

Chromosomes are found

A

in the nucleus

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22
Q

Chromosomes are made up from

A

DNA

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23
Q

Put the following in order of size starting with the smallest

cell, gene, nucleus, chromosome

A

gene, chromosome, nucleus, cell

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24
Q

What are genes?

A

Short sections on DNA found on chromosomes - they code for a particular characteristic

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25
Q

How are mitosis and meiosis different?

A

Mitosis is used for growth and repair, meiosis makes gametes

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26
Q

How many times does the cell divide in meiosis?

A

twice

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27
Q

How are the cells produced different from the parent cell in meiosis

A

they have half the chromosome number

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28
Q

How many cells are produced at the end of meiosis?

A

4

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29
Q

How many cells are produced at the end of mitosis?

A

2

30
Q

At fertilisation what happens to the chromosome number?

A

It doubles and chromosome number is restored.

31
Q

In the first step in meiosis what has to happen?

A

DNA/chromosomes copy/replicate themselves

32
Q

Are the cells produced at the end of meiosis genetically identical or genetically different?

A

genetically different

33
Q

During fertilisation what happens?

A

egg and sperm cell fuse together

34
Q

Following fertilisation, what cell is made?

A

Zygote (fertilised egg)

35
Q

What happens to the the fertilsed egg made following fertilisation?

A

It will divide by mitosis, cell number will increase to form an embryo and then eventually a foetus

36
Q

What makes an embyro and a foetus different?

A

A embryo contains unspecialised cells, a foetus contains cells that have begun to specialise - they have differentiated.

37
Q

What does differentiation mean?

A

When cells (in an embryo) begin to specialise

38
Q

Give an example of a specialised cell

A

muscle, red blood cell, nerve

39
Q

What is the genome?

A

It describes all of the genetic material that an organism has

40
Q

Describe the structure of DNA

A

Double helix

41
Q

Where is your DNA found?

A

In the nucleus in the form of chromosomes

42
Q

How are genes and proteins linked together?

A

genes (code for characteristics) code for a sequence of amino acids that make a protein

43
Q

Why is studying the genome important?

A

Search and study genes that cause disease, then try and treat the disease

44
Q

A DNA polymer is made up of…

A

repeating nucleotide units/monomers

45
Q

Define phenotype

A

outward appearance

46
Q

define genotype

A

combination of alleles

47
Q

Where are proteins synthesised?

A

ribosomes

48
Q

What types of jobs can proteins have?

A

enzymes, hormones, structural proteins e.g. collagen

49
Q

Of the 23 pairs of chromosomes in a body cell, how many control characteristics only?

A

22

50
Q

The 23 rd pair of chromosomes is called the sex chromosomes, what they in females and males?

A

females - XX

males XY

51
Q

Name a genetic disorder that is inherited

A

cystic fibrosis or polydactyl

52
Q

What is polydactyl?

A

Having extra digits

53
Q

What is polydactyl caused by?

A

A dominant allele

54
Q

What is cystic fibrosis?

A

A disorder of the cell membranes

55
Q

What is cystic fibrosis caused by?

A

A recessive allele

56
Q

Name characteristic caused by a SINGLE gene

A

tongue rolling, attached ear lobes

57
Q

Name characteristics caused by MULTIPLE genes

A

eye colour, hair colour, height, nose shape

58
Q

What is a dominant allele?

A

where only one copy of the allele is required to express that trait -this allele is always expressed if present

59
Q

What is a recessive allele?

A

where two copies are required to express that trait, its not expressed in presence of a dominant allele

60
Q

What does homozygous mean?

A

Where you have two copies of the SAME allele for a given characteristic e.g. BB, bb

61
Q

What does heterozygous mean?

A

Where you have 2 different copies of an allele for a given characteristic e.g. Bb

62
Q

What is an allele?

A

A different version of the same gene e.g. blue eyed allele, green eyed allele, brown eyed allele

63
Q

What are enzymes?

A

Proteins that are biological catalysts

64
Q

What are hormones?

A

Chemical messengers that travel in the blood stream to a target organ

65
Q

Do gametes have one or two copies of each chromosome?

A

one

66
Q

What are the chances of have a pregnant lady have a boy?

A

50%

67
Q

What sex chromosome do you find in a sperm?

A

X or a Y

68
Q

What sex chromosome do you find in an egg cell?

A

X only

69
Q

What sex determines the sex of the child?

A

Father - you will always receive an X from mum and then X OR Y from dad

70
Q

How could you determine whether a pregnant woman was carrying a child with a genetic disorder?

A

embryo screening

71
Q

Why might people be against embryo screening?

A

its expensive, may lead to designer babies and all parents wanting to screen embryos and pick the most desirable

72
Q

Why are people for embryo screening?

A

stops suffering
treating disorders can be expensive
there are laws to stop it going too far

SHHS - Science - AQA Biology Trilogy (37 decks)

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