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

4.6 Reproduction TRIPLE Flashcards

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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

Give an advantage of sexual reproduction

A

produces variation in offspring giving it a survival advantage if the environment changes

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20
Q

Give a disadvantage of sexual reproduction

A

need 2 parents, more energy is needed, slower process and fewer offspring produced

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21
Q

Give an advantage of asexual reproduction

A

Only need one parent, less energy is needed (more energy efficient), faster than sexual reproduction

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22
Q

Give a disadvantage of asexual reproduction

A

No variation, therefore susceptible to environmental changes

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23
Q

How many chromosome pairs are found in human body cells?

A

23 pairs

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24
Q

How many chromosomes are found in human sex cells

A

23

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25
Q

Chromosomes are found

A

in the nucleus

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26
Q

Chromosomes are made up from

A

DNA

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27
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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28
Q

What are genes?

A

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

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29
Q

How are mitosis and meiosis different?

A

Mitosis is used for growth and repair, meiosis makes gametes

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30
Q

How many times does the cell divide in meiosis?

A

twice

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31
Q

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

A

they have half the chromosome number

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32
Q

How many cells are produced at the end of meiosis?

A

4

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33
Q

How many cells are produced at the end of mitosis?

A

2

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34
Q

At fertilisation what happens to the chromosome number?

A

It doubles and chromosome number is restored.

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35
Q

In the first step in meiosis what has to happen?

A

DNA/chromosomes copy/replicate themselves

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36
Q

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

A

genetically different

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37
Q

During fertilisation what happens?

A

egg and sperm cell fuse together

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38
Q

Following fertilisation, what cell is made?

A

Zygote (fertilised egg)

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39
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

40
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.

41
Q

What does differentiation mean?

A

When cells (in an embryo) begin to specialise

42
Q

Give an example of a specialised cell

A

muscle, red blood cell, nerve

43
Q

What is the genome?

A

It describes all of the genetic material that an organism has

44
Q

Describe the structure of DNA

A

Double helix

45
Q

Where is your DNA found?

A

In the nucleus in the form of chromosomes

46
Q

How are genes and proteins linked together?

A

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

47
Q

Why is studying the genome important?

A

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

48
Q

TRIPLE DNA is a polymer made from 4 different nucleotides - what are nucleotides made from?

A

base, sugar and phosphate

49
Q

TRIPLE Name the bases found in DNA

A

A, T, G and C

50
Q

TRIPLE Which bases pair together?

A

AT and GC

51
Q

TRIPLE How do the bases code particular amino acid sequence?

A

Sequence of bases grouped into 3s, every 3 bases codes for a specific amino acid

52
Q

TRIPLE What do the order of the bases in DNA detemermine?

A

The order of the amino acids that make up the protein

53
Q

TRIPLE In a long DNA molecule how are the sugar and phosphate arranged?

A

alternating

54
Q

TRIPLE Which part of the nucleotide is the base attached to?

A

the sugar

55
Q

A DNA polymer is made up of…

A

repeating nucleotide units/monomers

56
Q

Define phenotype

A

outward appearance

57
Q

define genotype

A

combination of alleles

58
Q

Where are proteins synthesised?

A

ribosomes

59
Q

TRIPLE When a protein in synthesised using DNA what carries the message to the ribosomes

A

template - mRNA

60
Q

TRIPLE what molecule brings in specific amino acids according to the template to make a protein?

A

carrier molecules (tRNA)

61
Q

TRIPLE When protein synthesis is complete what happens to the synthesised protein?

A

It folds up into a unique shape

62
Q

What types of jobs can proteins have?

A

enzymes, hormones, structural proteins e.g. collagen

63
Q

TRIPLE What is a mutation?

A

A change in the base sequence of DNA

64
Q

TRIPLE what effect can mutations in DNA have on proteins?

A

Some may have no effect, others may completely alter the protein e.g. an enzyme no longer fits its substrate

65
Q

TRIPLE Which parts of the DNA molecule DO NOT code for proteins?

A

Non-coding sections

66
Q

TRIPLE What role can these non-coding portions have?

A

They can switch genes on or off

67
Q

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

A

22

68
Q

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

A

females - XX

males XY

69
Q

Name a genetic disorder that is inherited

A

cystic fibrosis or polydactyl

70
Q

What is polydactyl?

A

Having extra digits

71
Q

What is polydactyl caused by?

A

A dominant allele

72
Q

What is cystic fibrosis?

A

A disorder of the cell membranes

73
Q

What is cystic fibrosis caused by?

A

A recessive allele

74
Q

Name characteristic caused by a SINGLE gene

A

tongue rolling, attached ear lobes

75
Q

Name characteristics caused by MULTIPLE genes

A

eye colour, hair colour, height, nose shape

76
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

77
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

78
Q

What does homozygous mean?

A

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

79
Q

What does heterozygous mean?

A

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

80
Q

What is an allele?

A

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

81
Q

What are enzymes?

A

Proteins that are biological catalysts

82
Q

What are hormones?

A

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

83
Q

TRIPLE: What is mRNA

A

a molecule that carries the DNA code to the ribosomes from the nucleus

84
Q

TRIPLE: When do mutations occur

A

randomly

85
Q

TRIPLE: When can mutation rate be increased?

A

exposure to UV, chemical carcinogens, radiation

86
Q

TRIPLE: A mutation changes the DNA base sequence of a gene - what does this create?

A

a different version of the gene - a new allele

87
Q

TRIPLE: Give some examples of mutations

A

insertion, deletion and substitution

88
Q

Do gametes have one or two copies of each chromosome?

A

one

89
Q

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

A

50%

90
Q

What sex chromosome do you find in a sperm?

A

X or a Y

91
Q

What sex chromosome do you find in an egg cell?

A

X only

92
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

93
Q

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

A

embryo screening

94
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

95
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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