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reproduction and inheritance Flashcards

(71 cards)

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1
Q

where is all genetic material in the form of chromosomes

A

in the nucleus

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2
Q

what is a chromosome

A

long length of DNA coiled up

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3
Q

what is a gene

A

a short section of DNA

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4
Q

what does diploid mean and where are they found

A

have two copies of each chromosome and are arranged in pairs. these occur in human cells

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5
Q

how many chromosomes does a healthy human have

A

46 23 pairs

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6
Q

what are genes

A

chemical instructions

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7
Q

what is DNA

A

a long list of instructions on how to put an organism together and make it work

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8
Q

why are proteins important

A

control most processes in the body

they determine inherited characteristics e.g eye colour, blood type

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9
Q

what controls the production of proteins

A

genes (so they also control are inherited characteristics)

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10
Q

what does DNA appear as

A

a double helix (two spirals)

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11
Q

what hold two strands together in DNA

A

Bases

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12
Q

what are the four different bases

A

(A) adenine (C) cytosine (G) guanine (T) thymine

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13
Q

what are the two pairs of bases

A

A-T C-G
adenine + thymine
cytosine + guanine

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14
Q

why do genes always come in pairs

A

one is from farther and the other is from the mother

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15
Q

what are the two ways an organism can reproduce

A

sexually and asexual

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16
Q

definition of asexual reproduction

A

involves only one parent. The offspring have identical genes to the parent - so there’s no variation between parent and offspring.

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17
Q

name a form of asexual reproduction

A

mitosis (involves two cells dividing in two and forming an extra cell genetically the same to the other)

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18
Q

give a definition of mitosis

A

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

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19
Q

list the steps of mitosis

A

in a cell that’s not dividing, the DNA is all spread out in long strings
1. if the cell gets a signal to divide, it needs to duplicate its DNA so there’s only one copy for each new cell.
The DNA forms X-shaped chromosoms. Each ‘arm’ of the chromosome is an exact duplicate of the other.

  1. The chromosomes then line up at the centre of the cell and cell fibres pall them apath
  2. membranes form aound each of the sets of chromosomes these become nuceli of the new cells
  3. lastly cytoplasm divides
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20
Q

how is mitosis used in the human body

A

for growth and repair

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21
Q

give a definition of sexual reproduction

A

sexual reproduction involves the fusion of the male and female gametes.
Because there are TWO parents, the offspring contain a mixture of their parents’ genes

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22
Q

what is the difference between meiosis and mitosis

A

Meiosis produces four haploid cells whose chromosomes are NOT identical

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23
Q

list the steps of meiosis

A

step 1
same as start of mitosis

step 2
chromosomes in both cells line up and then split again and left with 4 haploid cells

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24
Q

what is the name of the male reproductive part of the plant

A

staMEN

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25
what is the name of the female reproductive part of the plant
carpel
26
what does the stamen consist of
anther and filament
27
what does the carpel consist of
ovary, style and stigma
28
what does the anther contain
pollen (male gamete)
29
what is the filament
is the stalk that supports the anther
30
what is the stigma
the end bit that the pollen grains attach to
31
what is the style
rod like section that supports the stigma
32
what is the ovary
contains the female gamete inside ovules
33
what is pollination
the transfer of pollen from an anther to a stigma, so that the male gametes can fertilise the female gametes
34
what is cross pollination
type of sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another plants which cross pollinated rely on wind and insects
35
how are some plants adapted for insect pollination
brightly coloured petals scented flowers big sticky pollen grains stigma is sticky so pollen can be picked up from insects
36
how are some plants adapted for wind pollination
``` small dull petals no strong scent lots of pollen grains long filaments that hang from the anther large feathery stigma to catch pollen ```
37
what is fertilisation
the fusion of gametes
38
list the stages of fertilisation in a plant
1. pollen grains land on the stigma 2. pollen tube grows out of the pollen grain and down through the style to the ovary and into the ovule 3. nucleus from the male gamete moves down the tube to join with a female gamete in the ovule 4. each fertilised female gamete forms a seed. The ovary develop into a fruit around the seed.
39
what is germination
when a seed starts to grow
40
what 3 thing does a plant need for germination
1. Water - to activate the enzymes that break down the food reserves in the seed 2. oxygen - for respiration, which provides the energy for growth 3. a suitabl temperature - for enzymes inside the seed to work
41
what does a developed seed contain
an embryo and a store of food reserves
42
name two methods of natural asexual reproduction in plants
1. runners | 2. tubers
43
give an example of runners and describe how they work
strawberry plants 1. The parent strawberry plant sends out runners - fast growing stems that grow out sideways, just above the ground 2. The runners take root at various points and new plants start to grow 3. The new plants are clones of the parent strawberry plant, so there's no genetic variation between them.
44
name a method of artificial asexual reproduction in plants
cuttings
45
how are cuttings taken from a plant
1. cuttings are taken each with a new bud on 2. The cuttings are kept in most conditions until they are ready to plat 3. cloned plant produced
46
learn both diagrams on page 57
learn 57
47
what is the male hormone called
testosterone
48
what do hormones do
promote sexual characteristics at puberty
49
what does testosterone do
1) extra hair on face and body 2) muscles develop 3) Penis and testicles enlarge 4) sperm production 5) deepening voice
50
what is the female hormone
oestrogen
51
what are the effects of oestrogen
1) extra hair on underarms and pubic area 2) hips to widen 3) ovum releases and start of periods
52
what happens at each stage in the menstrual cycle
stage 1) bleeding starts, the uterus lining breaks down for about for days stage 2) the uterus lining builds up again from day 4 to 14 stage 3) an ovum develop[s and is released from the ovary at day 14 stage 4) the wall is then maintained for about 14 days days 14-28 if no fertilisation lining will begin to break down again
53
what controls the menstrual cycle
oestrogen | progesterone
54
what does oestrogen do (menstrual cycle)
1. causes the lining of he uterus to thicken and grow | 2. stimulates the release of an ovum at day 14
55
what does progesterone do (menstrual cycle)
maintains the lining of the uterus. When the level of progesterone falls the lining breaks down
56
what is the role of the placenta
to have blood pass very close to the mothers blood to exchange food, oxygen and waste
57
what are Alleles
different versions of the same Gene
58
what does homozygous mean
for a trait you have two alleles which are the same
59
what is a genotype
the alleles you have
60
what is your phenotype
characteristics the alleles produce
61
what is codominance
when Neither allele is recessive so you show both characteristics, e.g blood
62
do men have the xx chromosome or XY
Xy
63
which parent has the y chromosome
dad
64
What causes Genetic Variation is caused by
Genes
65
name another factor which can cause variation in animals
The environment
66
list 4 factors in a human which isn't effected by the environment
1) Eye colour 2) Hair colour (in most humans) 3) Inherited disorders 4) blood group
67
what is the theory of evolution
Life began as simple organisms from which more complex organisms evolved
68
alist the steps of natural selection
1. living things show variation 2. the resources living things need to survive are limited individuals need 3. some varieties of a species have a better chance of survival so have an increased chance of breeding 4. next generation have a grater proportion of individuals in the next generation will have better alleles 5. over many generations, the species becomes better and better able to survie
69
what is a mutation
a rare random change in an organisms DNA that can be inherited
70
how can a mutation be caused
when a chromosome doesn't quite copy itself properly
71
what can cause cancer
a mutation may start to multiply in a uncontrollable way

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