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GCSE bio > section 7 - reproduction and inheritance > Flashcards

section 7 - reproduction and inheritance Flashcards

1
Q

what is a gene

A

short section of DNA that codes for a particular protein

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2
Q

how many chromosomes in a human body cell

A

diploid - 46

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3
Q

what are different versions of the same gene

A

alleles - blue or brown eyes

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4
Q

what are two strands of DNA

A

double helix

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5
Q

what are the two strands held together by

A

chemicals called bases

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6
Q

what are the 4 bases

A

adenine, cytosine, guanine, thymine

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7
Q

which base is A paired with

A

T

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8
Q

which base is C paired with

A

G

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9
Q

what does DNA control

A

production of proteins - protein synthesis in a cell

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10
Q

what does each protein have

A

a particular number and order of amino acids

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11
Q

what decides the order of amino acids in a protein

A

the order of bases

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12
Q

how many bases in a codon

A

3

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13
Q

how do genes code for a particular protein

A

contain different sequences of bases

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14
Q

DNA also contains non-coding regions means…

A

they dont code for any amino acids

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15
Q

what cell are proteins made in

A

ribosomes in the cytoplasm

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16
Q

why cant DNA move out of the nucleus

A

its to big

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17
Q

what is the molecule that get the information from the nucleus to the ribosome

A

mRNA

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18
Q

what is mRNA made up of

A

sequence of bases that is shorter and a single strand

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19
Q

what is the enzyme that joins together the base sequence to make mRNA

A

RNA polymerase

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20
Q

what are the steps of transcription

A
  1. RNA polymerase brings a region of non-coining DNA in front of a gene
  2. the two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA
  3. it uses the coding DNA in the gene as a template to make mRNA. base painting between DNA and RNA ensures that mRNA is complementary to the gene.
  4. once made the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm
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21
Q

what does mRNA use instead of T

A

U - uracil that pairs with A

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22
Q

what are the steps of translation

A
  1. amino acids are brought to the ribosome by another RNA molecule called tRNA
  2. the order in which the amino acids are brought to the ribosome matches the order of the codons in mRNA.
  3. part of the tRNA structure is called an anticodon - it is complementary to the codon for the amino acid. the pairing of the codon and anticodon make sure that the amino acids are brought to the ribosome in the correct order.
  4. the amino acids are joined together by the ribosome. this makes a protein.
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23
Q

what cell decision is asexual reproduction

A

mitosis - genetically identical and contain exactly same genetic information

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24
Q

what is the definition of asexual reprodiction

A

involves one parent. the offspring have identical genes to the parent - so there is no variation between parent and offspring

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25
Q

definition of mitosis

A

when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes

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26
Q

what is the 1st stage of mitosis

A

interphase - The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.

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27
Q

what is the 2nd stage of mitosis

A

Prophase- The DNA in chromosomes and their copies condenses to become more visible. The membrane around the nucleus disappears.

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28
Q

what’s the 3rd stage of mitosis

A

Metaphase Chromosomes and their copies line up in the middle of the cell.

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29
Q

what the 4th stage of mitosis

A

Anaphase Chromosomes and their copies are pulled to different ends of the cell by cell fibres

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30
Q

what is the 5th stage of mitosis

A

Telophase New membranes form around the chromosomes at each end of the cell.

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31
Q

what is Cytokinesis

A

The cell membrane pinches in and eventually divides into two daughter cells.

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32
Q

what is mitosis used for

A

growth and repair

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33
Q

how many daughter cells in mitosis and how many chromosomes

A

2 genetically identical diploid cells with 46 chromosomes

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34
Q

what are gametes

A

sperm and egg cells

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35
Q

how many chromosomes in gametes

A

haploid 23

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36
Q

what does the fuse of gametes cause

A

zygote with full set of chromosomes

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37
Q

definition of sexual reproduction

A

involves the fusion of male and female gametes because there are to parents, the offspring contain a mixture of their parents genes

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38
Q

where does meiosis happen

A

gametes

39
Q

definition of meiosis

A

produces 4 haploid cells whose chromosomes are not identical

40
Q

what happens in division 1 of meiosis

A
  1. DNA duplicates and one arm is the exact copy of other arm
  2. chromosomes line up in pairs at centre. one chromosomes in each pair comes from mother and one from father.
  3. the pairs are pulled apart so new cell has copy of Rach chromosome. some are mothers and some are fathers go into each new cell
  4. each new cell with have a mixture of mothers and fathers chromosomes which cause genetic variation
41
Q

what happens in division 2 of meiosis

A
  1. the chromosomes line up again in the centre of the cell. the arms of the chromosomes are pulled apart
  2. 4 haploid gametes. each gamete only has a single set of chromosomes and they are genetically different
42
Q

4 differences between mitosis and meiosis

A

mitosis produces 46 chromosomes - diploid. meiosis produced 23 chromosomes - haploid
mitosis produces 2 daughter cells, meiosis produces 4.
mitosis is for growth and repair and asexual reproduction and meiosis is for gametes only.
mitosis daughter cells are genetically identical. meiosis are all genetically different.

43
Q

what is the male part of the plant and what does it contain

A

stamen - filament and anther

44
Q

what is the function of the anther

A

contains pollen grains - produce male gametes

45
Q

what is the function of the filament

A

supports the anther

46
Q

what is the famale part of the plant

A

carpel - ovary, style and stigma

47
Q

what is the function of the stigma

A

pollen grains attach to

48
Q

what is the function of the style

A

supports the stigma

49
Q

what is the function of the ovary

A

contains female gametes inside ovules

50
Q

what is pollination

A

transfer of pollen from an anther to a stigma so male gametes can fertilise the female gametes in sexual reproduction

51
Q

what is cross-pollination

A

sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another

52
Q

what helps a plant pollinate

A

insects , wind

53
Q

how are plants adapted for insect pollination

A
  1. bright coloured petals to attract insects
  2. scented to attract
  3. big, sticky pollen grains to stick to insects as they go from plant to plant
  4. the stigma is also sticky so that any pollen will stick
54
Q

how are plants adapted for wind pollination

A
  1. small dull petals
  2. a lot of small and light pollen grains to be carried by the wind
  3. long filament that hang the anthers outside the flower to get blown by the wind
55
Q

how are plants adapted for wind pollination

A
  1. small dull petals
  2. a lot of small and light pollen grains to be carried by the wind
  3. long filament that hang the anthers outside the flower to get blown by the wind
  4. a large feathery stigma to catch pollen that hangs outside flower to
56
Q

what is fertilisation

A

the fusion of gametes

57
Q

what are the steps of plant fertilisation

A
  1. After pollen has landed on the stigma, it grows a pollen tube down through the style to the ovary.
  2. The nucleus of the pollen grain travels down the pollen tube and fertilises the nucleus in the ovule.
  3. The fertilised ovule develops into a seed. The seed contains the plant embryo, which contains genetic material from both parents. The ovary develops into the fruit.
58
Q

what are the conditions for a seed to germinate

A

water - to activate the enzymes that break down the food reserves in the heat
oxygen - for respiration
suitable temp - for enzymes to work

59
Q

how do germinating seeds get energy

A

from food stores

60
Q

what conditions would each of 4 tubes have in to investigate the conditions needed for germination

A

tube 1: water, oxygen, room temperature (control).
tube 2: no water, oxygen, room temperature
tube 3: water, oxygen, low temperature
tube 4: water, no oxygen, room temperature

61
Q

what are the observations from the conditions needed for germination

A

only see germination in tube 1 because all conditions are needed for germination are present

62
Q

what is a natural method for plants to clone

A
  1. runners - fast growing stems
  2. the runner take root at various points
  3. the new plants are clones of the parent plant
63
Q

what is an artificial method to clone plants

A

taking cuttings
cuttings kept in moist conditions until ready to plant. cloned plant

64
Q

what is the prostate gland for?

A

produce liquid thats added to sperm to make semen

65
Q

what is the urethra for

A

carries sperm or urine out of the body

66
Q

what is the testis for

A

where sperm is made

67
Q

what is the vas deferens

A

carries sperm from testis towards urethra

68
Q

what is the erectile tissue for

A

swells up when filled with blood to make penis errect

69
Q

what is the endometrium

A

lining of the uterus with good blood supply for implantation of an embryo

70
Q

what are female secondary characteristics

A
  1. extra hair on underarms or pubic area
  2. hips widen
  3. development of breasts
  4. ovum release and start of periods
71
Q

what are male secondary characteristics

A
  1. extra hair on face and body
  2. muscles start to develop
  3. penis and testicles to enlarge
  4. sperm production
  5. deepening voice
72
Q

what does FSH stimulate

A

egg to mature in follicle, stimulates ovaries to produce oestrogen and oestrogen inhibits release of FSH

73
Q

what does oestrogen stimulate

A

lining of uterus to grow, stimulates release of LH

74
Q

what does LH stimulate

A

stimulates release of egg at day 14

75
Q

what does progesterone stimulate

A

maintains the lining of the uterus. the level of progesterone falls, the lining breaks down. inhibits the release of LH and FSH.

76
Q

what is the placenta for?

A

blood of embryo and mother to get very close to allow the exchange of food, oxygen and waste

77
Q

what is the amniotic fluid for?

A

protects the embryo against knocks and bumps

78
Q

what is your genotype

A

the alleles that you have

79
Q

what is the phenotype

A

the characteristics the alleles produce

80
Q

what is homozygous

A

two of the same alleles

81
Q

what is heterozygous

A

two different alleles

82
Q

what are coo dominant alleles

A

both characterists from both alleles like blood group AB

83
Q

what are male chromosomes

A

xy

84
Q

what are female chromosomes

A

xx

85
Q

what is variation caused by

A

genetic and environmental factors

86
Q

what is a genetic factor

A

eye colour, hair colour

87
Q

what is an environmental factor

A

poor diet can stunt growth

88
Q

4 things plants are strongly affected by

A
  1. sunlight
  2. moisture level
  3. temperature
  4. mineral content in soil
89
Q

what is the theory of evolution

A

life began as simple organisms from which more complex organisms evolved

90
Q

what is natural selection

A
  1. genetic variation in characterists
  2. most suitable characterists for that environment would have a better chance of survival
  3. breed and reproduce
  4. pass on alleles
91
Q

how do mutations produce genetic variant

A

change the sequence of the DNA bases in a gene

92
Q

how do mutations increase variation

A

lead to different phenotype

93
Q

what are 2 reasons for the chance of mutation to be increased from exposure

A
  • ionising radiation
  • chemicals called mutagens like in tabacoo
94
Q

what is a superbug

A

bacteria that are resistant to most known antibiotics and are becoming more common

GCSE bio (8 decks)

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