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CGP Biology > Section 7 - Reproduction and Inheritance P1 > Flashcards

Section 7 - Reproduction and Inheritance P1 Flashcards

1
Q

What’s asexual reproduction?

A

Asexual reproduction 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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2
Q

Define mitosis:

A

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

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3
Q

What’s the use of mitosis?

A

To make new cells for growth and repair

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4
Q

What is the process of mitosis?

A
  • a cell duplicates its DNA, this forms an ‘X’ shaped chromosome (each ‘arm’ of the chromosome is an exact duplicate)
  • the chromosomes line up at the centre and cell fibres pull them apart,they go to opposite end of the cell after
  • membranes form around the two sets of chromosomes and these become nuclei
  • the cytoplasm divides, now have two new genetically identical cells
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5
Q

What are natural methods of asexual reproduction?

A

Strawberry plants send out runners(fast growing stems) that grow sideways just above the ground
These runners take root at various points(a short distance away) and new plants start to grow
The new plants are clones of the parent strawberry plant so there’s no genetic variation between them

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6
Q

What are artificial methods of asexual reproduction?

A

Gardeners have used cuttings for many years
They take cuttings from good plants, and then plant them to produce genetically identical copies(clones) of the parent plant
This can be done quickly and cheaply

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7
Q

What is sexual reproduction?

A

Sexual reproduction involves the fusion of male and female gametes. Because there are two parents, the offspring contains a mixture of their parents’ genes.

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8
Q

What does haploid mean in terms of cells?

A

They have half the number of chromosomes in a normal cell

-in humans haploid cells have 23 chromosomes

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9
Q

What is meiosis?

A

Meiosis is another type of cell division.

Meiosis produces four haploid cells whose chromosomes are not identical

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10
Q

What is the process of meiosis?

A

Has two divisions, the first similar to mitosis, the second not

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11
Q

What is the processes that go in the first division of meiosis?

A
  • DNA duplicates, form ‘X’ shaped identical pairs
  • the chromosomes line up in pairs in the centre
  • pairs are pulled apart so some chromosomes from the mother and some from the father go into each new cell (this is important for genetic variation)
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12
Q

What is the processes that go on in the second division of meiosis?

A
  • chromosomes line up in the centre of the cell again, they then split
  • you get four haploid cells as a result, with each gamete having one set of chromosomes and all are genetically different
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13
Q

What is the sexual organ of a plant?

A

The flower-it contains both male and female gametes

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14
Q

What’s the male reproductive parts of a flower and what is it made up of?

A

Stamen-Male reproductive parts

  • anther(contains pollen grains[male gametes])
  • filament(it is the stalk that supports the anther)
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15
Q

What’s the female reproductive parts of a flower and what is it made up of?

A

Carpel-Female reproductive parts

  • stigma(the bit that the pollen grain attaches to)
  • style(rod like section that supports the stigma)
  • ovary(contains the eggs[female gametes] inside the ovule)
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16
Q

What is pollination?

A

Pollination is the transfer of pollen from an anther to a stigma, so that the male gametes can fertilise the female gametes in sexual reproduction.

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17
Q

What is cross-pollination?

A

Cross-pollination is a type of sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another.

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18
Q

How do plants cross-pollinate?

A

They rely on things like insects or the wind to help them pollinate.

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19
Q

What are gametes?

A

Gametes are sperm and egg cells.

Gametes are haploid(this means they contain half the number of chromosomes of a normal cell, they have 23 chromosomes)

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20
Q

What’s fertilisation?

A

Fertilisation is when a male gamete fuses with a female gamete to form a zygote. The zygote ends up with a full set of chromosomes. The zygote then undergoes cell division and develops into an embryo.

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21
Q

How are some plants adapted for insect pollination?

A
  • brightly coloured petals(to attract insects)
  • scented flowers and nectaries(glands that produce nectar) to attract insects
  • make big, sticky pollen grains(the grains stick to insects as they go from plant to plant)
  • stigma is sticky so that pollen from insects sticks to the stigma
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22
Q

How are some plants adapted for wind pollination?

A
  • small, dull petals(don’t need to attract insects)
  • no nectaries or strong scents
  • a lot of small, light pollen grains(so they can be easily carried by the wind)
  • long filaments hang the anther outside of the flower(so lots of pollen gets blown away)
  • large, feathery stigma(to catch pollen from the wind)
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23
Q

What is the process of plant fertilisation?

A

1) pollen grain lands on stigma
2) pollen tube grows out of the pollen grain down into the ovule
3) a nucleus from the male gamete moves down the tube to join with the female gamete in the ovule
4) the two nuclei then fuse together(fertilisation)
5) the fertilised female gamete forms a seed, the ovary develops into a fruit around the seed

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24
Q

What is germination?

A

Germination is when a seed starts to grow

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25
What conditions are required for a seed to germinate?
A seed will often lie dormant until the conditions are right. - water(to activate the enzymes that break down food reserves in the seed) - oxygen(for respiration which transfers the energy from food for growth) - suitable temperature(for the enzymes)
26
What happens when a seed germinates?
1) seed takes in water and starts to grow using its store of energy 2) first root starts to grow down into the soil 3) shoot grows up 4) extra roots grow and the first green leaves appear
27
Where do germinating seeds get their energy from?
A developed seed contains an embryo and a store of food reserves, wrapped in a hard seed coat. When a seed starts to germinate, it gets glucose for respiration from its own food source Once a plant has grown enough to produce green leaves it then uses photosynthesis
28
What's an experiment to investigate the conditions needed for germination?
1) take four boiling tubes with cotton wool and 10 seeds in each 2) tube 1-water, oxygen, room temperature_tube 2-oxygen, room temperature_tube 3-water, oxygen, low temperature_tube 4-boiled water and oil, room temperature 3) leave the tubes for a few days and observe what has happened, you should only see germination in tube 1
29
What do the male reproductive parts make, and how is this used?
``` Make sperm(male gametes), made in the testes all the time after puberty -sperm mix with a liquid to make semen, which is ejaculated from the penis into the vagina during sexual intercourse ```
30
What is the urethra and where is it? (male)
Urethra-a tube which carries sperm through the penis during ejaculation, urine also passes through the urethra to exit the body -it's the tube down the inside of the penis
31
What's the glands and where are they located? (male)
Glands-produce a liquid that's added to sperm to make semen | -at the base of the penis
32
What's vas deferens and where is it located?
``` Vas deferens(sperm duct)-muscular tube that carries sperm from the testis towards the urethra -they are the tubes that lead to the testis ```
33
What's the scrotal sac and where is it located?
Scrotal sac(scrotum)-hangs behind the penis and contains the testes
34
What is erectile tissue?
Erectile tissue-swells when filled with blood to make the penis erect
35
What is a testis?
Where sperm are made
36
What does the female reproductive system make?
Ova(eggs), one is produced every 28 days
37
What is a oviduct?
oviduct(Fallopian tube) - a muscular tube that carries the ovum from the ovary to the uterus
38
What is an ovary?
Ovary-the organ that produces ova and sex hormones
39
What is the endometrium?
Endometrium(lining of the uterus)-has a good blood supply for implantation of an embryo
40
What's the uterus?
Uterus(womb)-where the embryo grows
41
What is the cervix?
Cervix-neck of the uterus
42
What is the hormone and secondary characteristics in men?
Hormone-testosterone Characteristics-extra hair on face and body, muscles to develop, penis and testicles enlarge, sperm production, deepening of voice
43
What is the hormone and secondary characteristics in women?
Hormone-Oestrogen Characteristics-extra hair on underarms and pubic area, hips to widen, development of breasts, ovum release and start of periods
44
What are the four stages of the menstrual cycle?
Stage1-menstruation starts(uterus lining breaks down for 4 days) Stage2-uterus lining builds up again day 4-14, into a thick, spongy layer full of blood vessels, ready to receive a fertilised egg Stage3-egg developers and is released day 14(ovulation) Stage4-wall is maintained day 14-28, if no fertilised egg has implanted the lining breaks down and the cycle starts again
45
What are the four hormones that control the menstrual cycle?
FSH Oestrogen LH Progesterone
46
Where is Oestrogen produced and what's its function?
- produced in the ovaries - cause the lining of the uterus to grow - stimulates the release of LH
47
Where is Progesterone produced and what's its function?
- produced in the ovaries by the remains of the follicle after ovulation - maintains the lining of the uterus during the second half of the cycle, when levels fall the lining breaks down - inhibits the release of LH and FSH
48
When does an embryo become a foetus?
After 8 weeks of development
49
What's the point in the amniotic sac(amnion membrane)?
It produces amniotic fluid and protects the developing embryo from knocks and bumps
50
When does the placenta develop and what's the purpose of the placenta?
The placenta develops once the embryo has implanted -materials pass by diffusion Materials that diffuse from the mother to the embryo:oxygen, glucose, amino acids, nutrients such as vitamins and minerals Materials the diffuse from the embryo to the mother:carbon dioxide, urea
51
Where are chromosomes found?
in the nucleus
52
What are chromosomes?
chromosomes are long lengths of DNA coiled up
53
What is a gene?
A gene is a short section of DNA
54
What type of cells are all human body cells?
Diploid - means they have two copies of each chromosome - contains 46 chromosomes
55
What is DNA?
a long list of instructions on how to put an organism together and make it work (chemical instructions)
56
What is a genone?
all of an organisms DNA
57
Why are proteins important?
they control most processes in the body | determine inherited characteristics
58
What are different versions of the same gene called?
alleles
59
What determines the characteristics that you develop?
What genes you inherit | -some characteristics are controlled by a single gene, most are controlled by several genes interacting
60
How many alleles do you inherit from your parents?
two alleles of each gene, so you have two copies of each gene (one from each parent)
61
What happens if the two alleles you inherit are different for a gene?
You have instructions for two different versions of a characteristic -only show one version of the two, the dominant allele is shown, and the other recessive allele isn't
62
When is a recessive allele's characteristic shown?
When both of the alleles are recessive
63
What is a genotype?
Your genotype is the alleles you have
64
What is a phenotype?
Your phenotype is the characteristics the alleles produce
65
In genetic diagrams, how are dominant and recessive alleles shown?
Dominant alleles are always shown with a capital letter | recessive alleles are always shown with a small letter
66
What does homozygous mean?
For a trait you have two alleles the same for that particular gene
67
What does heterozygous mean?
For a trait you have two different alleles for that particular gene
68
What is monohybrid inheritance?
The inheritance of a single characteristic
69
What can you use a monohybrid cross for?
To show how recessive and dominant traits for a single characteristic are inherited
70
How should you lay out a cross breeding question?
``` Parents' phenotype: Parents' genotype: Gametes' genotypes: (put the alleles separate in circles) Genetic cross: (Punnett square) Offspring's' genotype: Offspring's' phenotype: Ratio: ```
71
How can you draw a genetic diagram?
Using a Punnet square
72
How do you use a Punnet square?
draw a grid (3 x 3) - put the possible gametes from one parent down one side and the other across the top - in each of the middle squares fill in the pairs of letters (one from the column and one from the row), this shows all the possible combinations of the gametes
73
What is a family pedigree?
A family tree of genetic disorders
74
What chromosomes control whether you are male or female?
There are 23 matched pairs of chromosomes in every human body cell The 23rd pair is labelled XX or XY (they are the two chromosomes that decide whether you are male or female)
75
What chromosomes do males have?
Males have X and Y chromosomes (XY) | - the Y chromosome causes male characteristics
76
What chromosomes do females have?
Females have two X chromosomes (XX) | - XX combination causes female characteristics
77
What is the chance of having a boy or a girl?
There is an equal chance | 1 : 1 ratio
78
What determines the sex of a human child?
Whether the sperm that fertilises the egg carries an X or a Y chromosome
79
What is genetic variation?
Random mutations that occur in genes cause genetic mutations which cause genetic variation -all animals are different to each other because their genes are slightly different
80
What is variation in animals caused by?
A mix of genetic and environmental factors
81
What are aspects of humans which are determined solely by genes?
- eye colour - hair colour in most animals (in humans, vanity plays a big part) - inherited disorders (like haemophilia, cystic fibrosis..) - blood group
82
How can environment have an effect on humans even before they are born?
A babies birth weight can be affected by a mothers diet
83
What are some characteristics of animals that are affected by both genes and environment?
Health - some people are more likely to get certain diseases because of their genes, but lifestyle also affects the risk Intelligence - maximum possible IQ may be determined by genes, whether you get there can be affected by environment Sporting ability - genes determine potential, but training is important too
84
What factors create environmental variation in plants?
sunlight moisture level temperature mineral content of the soil
85
What factors create environmental variation in plants?
sunlight moisture level temperature mineral content of the soil
86
What is the theory of evolution?
Life began as simple organisms from which more complex organisms evolved
87
Who came up with the theory of evolution by natural selection?
Charles Darwin
88
What does natural selection mean?
Survival of the fittest
89
What are the differences between variations caused by the environment and genetic variation?
Genetic variations are passed on to the next generation and influence the evolution of a species
90
What are genetic mutations?
They are a rare, random change in an organism's DNA that can be inherited
91
How can bacteria evolve to become antibiotic-resistant?
- Bacteria can mutate, and sometimes the mutated bacterium is less affected by a particular antibiotic - the ability to resist antibiotics is a big advantage, it then reproduces more than others - the allele for resistance is then passed on to lots of offspring, this then becomes more common in a population of bacteria over time
92
Why is being able to resist antibiotics a big advantage for bacteria?
it able to survive better, even in a host who is being treated to get rid of the infection, so it lives longer and reproduces many more times than others
93
Why is bacteria being able to resist antibiotics a problem?
- people who become infected with this bacteria then can't easily get rid of them with antibiotics - drug companies can come up with new, effective antibiotics but 'superbugs' that are resistant to most known antibiotic are becoming more common
94
How do bacteria reproduce?
bacteria divide asexually – not by mitosis but by a process called Binary fission

CGP Biology (19 decks)

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