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Biology Revision 🌱 > Chapter 13 > Flashcards

Chapter 13 Flashcards

1
Q

what are the two types of reproduction?

A

sexual and asexual

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2
Q

how many parents in asexual?

A

1

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3
Q

how do cells divide in asexual reproduction?

A

mitosis (a cell divides in two to make new ones)

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4
Q

what is important to remember about the offspring of asexual reproduction?

A

they will be genetically identical to the parent

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5
Q

why will the offspring of asexual reproduction be genetically identical to the parent?

A

no fusion of gametes - the genetic information in the offspring will be identical to the parent

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6
Q

another name for the offspring of asexual reproduction?

A

clones

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7
Q

where is asexual reproduction most common? 4

A

bacteria
some plants and animals
human body cells

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8
Q

how many parents are involved in sexual reproduction?

A

2

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9
Q

what are the sex cells called?

A

gametes

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10
Q

what do the two sex cells fuse to form?

A

a zygote

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11
Q

how are gametes formed?

A

meiosis

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12
Q

what is important to remember about sex cells?

A

they have half the number of chromosomes so the zygote will have the correct number

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13
Q

how many chromosomes in a sperm or egg cell?

A

23

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14
Q

what is important to remember about the offspring of sexual reproduction?

A

they won’t be identical to the parents - variation

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15
Q

sex cells in plants

A

egg cells and pollen

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16
Q

why is variation important?

A

it allows variation in the offspring to adapt to changes in the surroundings

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17
Q

in humans, where does meiosis take place?

A

testes and ovaries

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18
Q

what does meiosis result in?

A

sex cells (gametes)

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19
Q

how many cell divisions are involved in meiosis?

A

2

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20
Q

why is there variation in offspring produced by sexual reproduction?

A

each gamete is different, and then this different gamete fuses with another gamete that is different to the parent, making more variation

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21
Q

process of meiosis

A
  1. the cell duplicates its genetic information (chromosomes) so there are 4 sets rather than the normal 2
  2. the cell then quickly divides twice to form 4 gametes each with a single set of chromosomes in
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22
Q

advantages of asexual reproduction

A

only one parent needed

uses less energy because no mate is needed - faster

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23
Q

advantages of sexual reproduction

A

variation

natural selection - better adapted animals pass on the genes needed for successful survival in this habitat

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24
Q

most common method of reproduction in fungi

A

asexual

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25
Q

name 3 examples of both asexual and sexual reproduction

A

plants
malaria parasite
fungi

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26
Q

how do fungi use both types of reproduction to their advantage?

A

they produce asexually when conditions for them are good and they have the adaptions needed to survive then reproduce sexually when conditions are bad and they need to adapt to survive

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27
Q

what is the disease called where a baby has extra fingers or toes?

A

polydactly

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28
Q

is polydactly dominant or recessive?

A

most commonly dominant

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29
Q

what is a punnet square?

A

a diagram that shows you the predicted outcomes of the children with certain diseases

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30
Q

what are the sex chromosomes of females?

A

XX

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31
Q

what are the sex chromosomes of males?

A

XY

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32
Q

how do malaria parasites reproduce both sexually and asexually?

A

in their host (the human) they will reproduce asexually to create lots of clones
in the mosquito, they will produce sexually to encourage variation as the mosquito is a lot cooler than the human and they need to be able to survive
they will then reproduce asexually in the mosquito to make as many parasites as possible

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33
Q

2 examples of asexual reproduction in plants

A

strawberry plants sprouting from runners

daffodils from bulbs

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34
Q

how do plants use sexual reproduction?

A

pollination - an insect carries pollen from one flower to another, creating new plants via sexual reproduction

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35
Q

what are the sex organs on a plant?

A

the flowers

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36
Q

what does DNA stand for?

A

deoxyribonucleic acid

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37
Q

what does DNA determine?

A

what characteristics you have

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38
Q

shape of DNA

A

double helix

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39
Q

what type of structure is DNA?

A

a polymer

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40
Q

what is a gene?

A

a small section of DNA found on a chromosome

41
Q

how many different amino acids are used?

A

20

42
Q

what does a gene do?

A

tells the cells what order to put the amino acids together in

43
Q

what is the genome?

A

the entire set of genetic material in an organism

44
Q

why do we need to understand the genome? 3

A

we can identify genes that cause different diseases
we can then develop better treatments for them
we can trace the migration of certain groups from around the world

45
Q

how many genes are in the human genome?

A

21,000

46
Q

what is DNA made from?

A

alternating phosphate and sugar sections

47
Q

what is a nucleotide?

A

a combination of a sugar, phosphate and base

48
Q

what are the four bases?

A

A, C, G, T

49
Q

what are the nucleotides grouped in?

A

3s

50
Q

what forms the backbone of the strand? (the single coloured section around the edge of the helix?

A

the phosphate and the sugar

51
Q

what does an A always pair with?

A

a T

52
Q

what does a C always pair with?

A

a G

53
Q

what can the non-coding part of DNA do?

A

turn genes on and off

54
Q

what is a mutation?

A

a random change in an organism’s DNA

55
Q

what is a phenotype?

A

physical expression of a gene combination

56
Q

what do mutations do?

A

change the sequence of DNA bases in a gene, so the protein it produces isn’t always correct

57
Q

2 serious impacts of mutations on proteins

A

the shape of an enzyme’s active site could change

structural proteins could lose their strength

58
Q

3 types of mutations

A

insertion
deletion
substitution

59
Q

how does insertion work?

A

a new base is inserted into the DNA sequence where it shouldn’t be

60
Q

how does deletion work?

A

a random base is deleted from the DNA sequence

61
Q

how does substitution work?

A

random bases in the DNA base sequence are changed for another base

62
Q

what is an allele?

A

a different form of a gene

63
Q

what is a homozygote?

A

an individual with 2 identical alleles for a characteristic, eg BB or bb

64
Q

what is a heterozygote?

A

an individual with 2 different alleles for a characteristic , eg Bb

65
Q

what is a genotype?

A

the genetic make up of an individual regarding a single characteristic

66
Q

what is a dominant allele?

A

the allele that overrules the recessive allele to show the characteristic in the person

67
Q

what must happen for an organism to display a recessive characteristic?

A

both of its alleles must be the same (bb)

68
Q

what is a genetic diagram?

A

models used to show all the possible expected genetic outcomes

69
Q

what are most characteristics a result of?

A

several genes interacting

70
Q

best diagram to show genetic outcomes?

A

Punnett square

71
Q

what to remember about showing a Punnett square in an exam?

A

write out all the possible outcomes, what they show and the probability (eg, black fur, 50%, BB)

72
Q

what do all human eggs contain?

A

an X chromosome

73
Q

what is cystic fibrosis?

A

when the body produces lots of thick, sticky mucus especially in the lungs

74
Q

which type of allele is cystic fibrosis caused by?

A

a recessive allele

75
Q

3 treatments for cystic fibrosis

A

physiotherapy
antibiotics
enzymes to replace ones the pancreas can’t secrete

76
Q

effect of cystic fibrosis on pancreas

A

the pancreas becomes clogged up and can’t secrete enzymes

77
Q

what is a carrier?

A

a person who is healthy but carries the recessive allele

78
Q

why must two people who are carriers create a child with cystic fibrosis?

A

it is a recessive allele

79
Q

how many people in the UK carry the cystic fibrosis allele?

A

4%

80
Q

what is genetic engineering?

A

when scientists replace faulty genes that cause a disorder with healthy ones

81
Q

when is amniocentesis carried out?

A

15-16 weeks

82
Q

process of amniocentesis

A

a needle is inserted into the amniotic sack, fluid is sucked up and then analysed

83
Q

main three ways of harvesting cells from embryos

A

amniocentesis
chorionic villus sampling
IVF

84
Q

when is chorionic villus sampling carried out?

A

between 10-12 weeks

85
Q

process of chorionic villus sampling

A

cells are taken from the developing placenta, either with a needle or catheter and then analysed

86
Q

advantages of offering genetic testing to all pregnant couples 3

A

can identify potentially fatal diseases
gives the parents the knowledge and option of what to do
allows a couple using IVF to have the best chances at a healthy, surviving baby

87
Q

disadvantages of offering genetic testing to all pregnant couples 3

A

expensive
the parents are faced with a very difficult decision
increased risk of miscarrying a healthy baby

88
Q

what will meiosis result in?

A

non-identical cells being formed

89
Q

what will mitosis result in?

A

identical cells being formed

90
Q

where is meiosis used?

A

to create sex cells

91
Q

process of meiosis

A

copies of genetic information are made
cell quickly divides twice to form 4 sets of gametes
these gametes have half the number of normal chromosomes

92
Q

what is important to remember about all gametes

A

they are genetically different

93
Q

what is an allele?

A

the different forms of a gene (i.e. dominant or recessive)

94
Q

what do non-coding parts of DNA do?

A

switch genes on and off

95
Q

process of protein synthesis?

A

DNA in the nucleus unravels
enzymes make a copy of the DNA called mRNA
mRNA travels from nucleus to ribosomes
ribosomes translate 3 bases into amino acids
ribosomes link amino acids to form a protein

96
Q

what is mRNA and what does it do?

A

Messenger RNA

it is a copy of the DNA sent from the nucleus to the ribosomes to code for proteins

97
Q

function of a gene?

A

it contains DNA

it codes for the production of a specific amino acid

98
Q

How are seeds produced?

A

Pollination of egg cells in one flower by pollen from another

99
Q

How are embryos screened for alleles that cause genetic disorders?

A

DNA isolated from embryo
Fluorescent probe mixed with embryo DNA
Probe binds to DNA
UV light shows up alleles for disorder

Biology Revision 🌱 (18 decks)

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