Reproduction and Inheritance - GCSE Flashcards
1
Q
where are chromosomes found?
A
in the nucleus of a cell
2
Q
what does the nucleus contain genetic material in the form of?
A
chromosomes
3
Q
what are chromosomes?
A
long lengths of DNA coiled up
4
Q
what is a gene?
A
a short section of DNA
5
Q
what are human cells?
A
they are diploid. Meaning they have two copies of each chromosome arranged in pairs
6
Q
how many chromosomes does a human cell nucleus contain?
A
- This means the diploid number for a human is 23
7
Q
what is DNA?
A
it is a long list of instructions of how to put an organism together and make it work
8
Q
what does all of the DNA in an organism make up?
A
the organism’s genome (a complete set of information in a organism)
9
Q
what is a gene (in a DNA molecule)?
A
it is a chemical instruction that codes for saying how to make a particular protein
10
Q
why are proteins important?
A
because they control most processes in the body. They also determine inherited characteristics (eg. eye colour)
11
Q
why do genes end up controlling our inherited characteristcs?
A
because they control the production of proteins, and therefore they control inherited characteristics as well
12
Q
what is the name for different versions of the same gene?
A
alleles
13
Q
what do alleles (different versions of the same gene) give?
A
they give different versions of a characteristic
14
Q
how can an ordinary cell make a new cell?
A
it can make a simple cell by simply dividing into two. Both new cells are genetically identical to the original cell and both contain exactly the same genetic information
15
Q
what is it called when an ordinary cell makes up new cells?
A
mitosis
16
Q
what is asexual reproduction?
A
it is when it only involves one parent, the offspring has identical genes to the parent (there is no variation between the parent and the offspring)
17
Q
what is it called when some organisms produce offspring using mitosis?
A
asexual reproduction (only one parent)
18
Q
what does mitosis produce?
A
genetical identical cells (when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes)
19
Q
what happens when a cell gets a signal to divide?
there are 4 steps
A
1) it needs to duplicate its DNA so that there’s on copy for each new cell. The DNA forms X-shaped chromosomes, each arm of the chromosome is an exact duplicate of the other
2) the chromosomes lines up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell
3) membrane form around each of the sets of chromosomes. These become the nuclei of the two new cell
4) lastly, the cytoplasm divides
20
Q
what does sexual reproduction produce?
A
genetically different cells
21
Q
what is sexual reproduction?
A
it is where information from two organisms (a father and a mother) is combined to produce offspring which are genetically different to either parent
22
Q
what does sexual reproduction involve?
A
it involves gametes
23
Q
what are gametes?
A
the sperm cells and egg cells. They are haploid as well.
24
Q
what does haploid mean?
A
it means half the number of chromosomes in a normal cell
25
what is the haploid number for humans?
23, because each gamete contains 23 chromosomes.
46 chromosomes/2 = 23
26
what happens at fertilisation?
a male gamete fuses with a female gamete to form a zygote. The zygote ends up with the full set of chromosomes (46 chromosomes)
27
what is a zygote?
a fertilised egg
28
what causes a zygote to be developed into an embryo?
the zygote undergoes cell division (by mitosis) and develops into an embryo
29
how does the embryo inherits features from both parents?
it receives a mixture of chromosomes from its mom and dad
30
what is the order for the fertilisation of gametes?
it is random. This produces genetic variation in the offspring
31
what are gametes produced by?
meiosis
32
what is a meiosis?
type of cell division
- produces 4 daughter cells
- offspring are different to parents
33
why is meiosis different to mitosis?
because it doesn't produce identical cells
34
where does meiosis happens in humans?
it only happens in the reproductive organs (ovaries and testes)
35
what do meiosis produce?
it produces four haploid cells whose chromosomes are not identical
36
how many divisions does meiosis involve?
2
37
what is the first part of the division of meiosis?
| there are 4 steps
1) before the cell starts to divide it duplicates its DNA. One arm of each X-shaped chromosome is an exact copy of the other arm
2) in the first division in meiosis the chromosome lines up in pairs in the centre of the cell. One chromosome in each pair came from the organism's mother and one came from its father
3) the pairs are then pulled apart, so each new cell only has one copy of each chromosome. Some of the father's chromosomes and some of the mother's go into each new cell
4) each new cell will have a mixture of the mother's and father's chromosome. Mixing up the genes like this is really important because it creates genetic variation in the offspring
38
what is the second part of the division of meiosis?
| 2 steps
5) chromosomes line up again in the centre of the cell. The arm of the chromosomes are pulled apart
6) you get four haploid gametes. Each gamete only has a single set of chromosomes. The gametes are all genetically different.
39
what gametes do flowers contain?
male and female gametes
40
what is the name of the male reproductive part of a flower?
the stamen
41
what are the 2 things that the stamen consists?
- anther
| - filament
42
what does the anther contain?
pollen grains, which produce the male gametes (sperm)
43
what is the filament?
the stalk that supports the anther
44
what is the name of the female reproductive part of a flower?
the carpel
45
what are the 3 things the carpel consist of?
- ovary
- style
- stigma
46
what is the stigma?
it is the end bit that the pollen grains attach to
47
what is the style?
it is the rod-like section that supports the stigma
48
what does the ovary contain?
the ovary contains the female gametes (eggs) inside the ovules
49
what does sexual reproduction in plants involve?
it involves pollination
50
what is pollination? and why does it happen?
the transfer of pollen from an anther to a stigma. It is so that the male gametes can fertilise the female gametes in sexual reproduction
51
what is cross-pollination?
it is a type of sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another
52
what do plants that cross-pollinate rely on?
they rely on things like insects or the wind to help them pollinate
53
what is it called when plants need outside help to pollinate?
insect pollination
54
what are 4 different ways that plants are adapted for pollination by insects?
1) brightly coloured petals
2) scented flowers and nectaries (glands that secrete nectar)
3) make big sticky pollen grains and thee grains stick to insects as they go from plant to plant
4) the stigma is sticky so that any pollen picked up by insects on other plants will stick to the stigma
55
other than insect pollination, what is another way for plant pollination?
pollination by wind
56
what are 5 ways in which plants are adapted for plant pollination?
1) small, dull petals on the flower
2) no nectaries or strong scents
3) a lot of pollen grains, they are small and light so that they can easily be carried by wind
4) long filaments that hang the anthers outside the flower so that a lot of the pollen gets blown away by the wind
5) a large feathery stigma to catch pollen as it's carried past by the wind. The stigma often hangs outside the flower too
57
what happens after the pollen has found its way to the stigma?
fertilisation
58
what is fertilisation?
it is when the two nuclei fuse together to make a zygote. This divides by mitosis to form an embryo
59
what are the 4 steps of fertilisation (in plants)?
1) pollen grain lands on the stigma of flower, usually with the help from insects or the wind
2) a pollen tube grows out of the pollen grain and down through the style to the ovary and into the ovule
3) a nucleus from the male gamete moves down the tube to join a female gamete in the ovule
4) each fertilised female gamete forms a seed. The ovary develops into a fruit around the seed
60
what does a seed need to start germinating?
the right conditions
61
what happens to a seed if it isn't on the right conditions?
it will lie dormant until the conditions are right for germination
62
what is germination?
when seeds start to grow
63
what are 3 things that need to be on the right conditions for a seed to start germinating?
- water
- oxygen
- temperature
64
why does water need to be on the right conditions for a seed to start germinating?
water is used to activate the enzymes that break down the food reserves in the seed
65
why does oxygen need to be on the right conditions for a seed to start germinating?
it needs to be right for the respiration of the plant, which transfers energy from food for growth
66
why does a suitable temperature need to be on the right conditions for a seed to start germinating?
it needs to be right for the enzymes inside the seed to work (this depends on what type of seed it is.
67
what does a developed seed contain?
an embryo and a store of food reserves, wrapped in a hard seed coat
68
how does a germinating seed get energy from food stores?
1) when a seed starts to germinate, it gets glucose for respiration from its own food store. This transfers the energy it needs to grow
2) once the plant has grown enough to produce green leaves it can get its own food for energy from photosynthesis
69
how do you investigate the conditions needed for germination?
(there are 6 steps)
IMPORTANT
tube 1 - water, oxygen, room temperature (control tube)
tube 2 - no water, oxygen, room temperature
tube 3 - water, oxygen, low temperature
tube 4 - water, no oxygen, room temperature
1) take four boiling tubes and put some cotton wool at the bottom of each one
2) put 10 seeds on top of the cotton wool in each boiling tube
3) set up each boiling tube
4) leave the tubes for a few days and then observe what has happened.
5) control all the variables during the experiment. Remember to only change one condition at a time so you know that any effect on germination is due to the change in that one tube
6) tube 2 the only change from the control tube (Tube 1) is lack of water. In tube 3 only the temperature has changed. In tube 4 the only change is the lack of oxygen
70
how should you interpret your observation from "How do you investigate the conditions needed for germination?" experiment?
You should only see germination happening in Tube 1 because all the conditions needed for germination are present.
The seeds in the other boiling tubes won't germinate, this is shows that the seeds need water, oxygen and suitable temperature to germinate
71
what are the two ways plants reproduce asexually?
- naturally
| - artificially (cloned)
72
how are plants artificially reproduced (how are they cloned)?
1) gardeners can take cutting from good parent plants, and then plant them to produce genetically identical copies (clones) of the parent plant.
2) these plants can be produced quickly and cheaply
73
how are plants naturally reproduced?
by growing new plants from their stems
74
how are strawberries naturally reproduced?
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 (a short distance away) 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
75
what does the male reproductive system make?
it makes sperm
76
what are sperms?
they are male gametes
77
where are the sperms made?
they are made in the testes ALL THE TIME after puberty
78
sperm mixed with a liquid make up what?
it makes up semen which is ejaculated from the penis into the vagina of the female during sexual intercourse
79
what is the urethra - male reproductive system
a tube which carries sperm through the penis during ejaculation . Urine also passes through the urethra to exit the body
80
what is the erectile tissue - male reproductive system
swells when filled with blood to make the penis erect
81
what is testis - male reproductive system
where sperm are made (the plural is testes)
82
what are the glands - male reproductive system
where the liquid that's added to sperm to make semen is produced
83
what is the vas deferens (sperm duct) - male reproductive system
muscular tube that carries sperm from testis towards the urethra
84
what is the scrotal sac - male reproductive system
it is what hangs behind the penis and contains the testes
85
remember what the male reproductive system diagram looks like -->
https://1.bp.blogspot.com/-jsasG6ZCXvM/XT7GKAV3D5I/AAAAAAAAAUw/ZFSsOOQ-iEgbE2bKVmWi9r1afLBCYQqoACLcBGAs/s1600/Screenshot%2B2019-07-29%2Bat%2B6.04.46%2BPM.png
86
what does the female reproductive system make?
it makes ova (eggs)
87
what is the ova?
female gametes
88
when is an ovum (egg) produced?
it is produced every 28 days from one of the two ovaries
89
after leaving one of the ovaries where does the ovum pass into?
it passes into the fallopian tube, this is where it might meet sperm that have entered the vagina during sexual intercourse
90
after the fallopian tube, what happens to the ovum tube if it isn't fertilised by sperm?
the ovum break up and pass out of the vagina
91
after the fallopian tube, what happens to the ovum tube if it is fertilised by sperm?
the ovum starts to divide, the new cells will travel down the fallopian tube to the uterus (womb) and attach to the endometrium (uterus lining)
92
what does a fertilised ovum develop into?
an embryo
93
what is the fallopian tube (oviduct) - female reproductive system
a muscular tube that carries the ovum from the ovary to the uterus
94
what is the uterus (womb) - female reproductive system
the organ where an embryo grows
95
what is the ovary - female reproductive system
the organ that produces ova and sex hormones
96
what is the edonmetrium (lining of uterus) - female reproductive system
it is where an implantation of an embryo would happen so it has a good blood supply
97
what is the cervix - female reproductive system
the neck of the uterus
98
what is the vagina - female reproductive system
where the sperm are deposited
99
remember what the female reproductive system diagram looks like -->
http://www.edplace.com/userfiles/female%20reproductive%20system.jpg
100
what do hormones promote at puberty? what are those hormones
sexual characteristics: they are sex hormones. Testosterone in men and oestrogen in women
101
what do the sex hormones in women (oestrogen) trigger/ causes?
- extra hair on underarms and pubic area
- hips to widen (important)
- development of breasts (important)
- menstruation cycle (important)
102
what do the sex hormones in men (testosterone) trigger/ causes?
- extra hair on face and body
- muscles to develop (important)
- penis and testicles to enlarge
- sperm production (important)
- deepening of voice (important)
103
how many stages does the menstrual cycles has?
four stages
104
what is the first stage of the menstrual cycle?
day one - menstruation starts. the uterus lining breaks down for about four days (lieee it is 5 but whatevs)
105
what is the second stage of the menstrual cycle?
the uterus lining builds up again, from day 4 to day 14 into thick spongy layer full of blood vessels, ready to receive a fertilised egg.
106
what is the third stage of the menstrual cycle?
an egg develops and is released from the ovary at day 14 - this is called ovulation
107
what is the fourth stage of the menstrual cycle?
the wall is then maintained for about 14 days until day 28- If no fertilised egg has landed on the uterus wall by day 28, the spongy lining starts to break down and the whole cycle starts again.
108
when does an embryo begin to become considered a fetus?
when it starts to look human
109
what develops once the embryo has been implanted?
the placenta develops, allowing the blood of the embryo and mother get very close to allow the exchange of food, oxygen and waste (the blood doesn't touch one another BECAUSE BLOOD CAN'T MIX TOGETHER)
110
other than the placenta, what else forms in the early stages of pregnancy?
the amnion membrane, which surrounds the embryo and is full of amniotic fluid. Amniotic fluid protects the embryo against knocks and bumps
111
what are alleles?
they are different versions of the same gene
112
what control the characteristics you develop?
the genes you inherit. Some characteristics can be controlled by a single gene however most are controlled by several genes interacting.
113
how many copies do you usually have of each gene?
most of the time you have two copies of each gene, one from each parent.
114
what happens if you inherit different alleles?
you will have instructions for two different versions of a characteristic but you only show one version of the two. The dominant allele always wins
115
what are the two alleles that fight together for a characteristic but one still always win?
the dominant - winner
| and the recessive - loser
116
actually, i was lying before, the recessive allele can win but only with one condition. what is that condition?
if both alleles are recessive (think of it from a point of both alleles becoming friends)
117
what is the name for the inheritance of a single characteristic?
monohybrid inheritance
118
what is used in genetic diagrams to represent genes?
letters. The dominant alleles are always shown with a capital letter and recessive alleles with a small letter
119
what does homozygous mean?
it means two alleles with the same for a particular gene (two dominants or two recessive)
120
what does heterozygous mean?
it means two different alleles for a particular gene (a dominant and a recessive)
121
what is your genotype?
it is the alleles that you have
122
what is you phenotype?
the characteristics the alleles produce
123
go to page 114 and 115 to learn about genetic diagrams
vai marcela para de ser preguiçosa
124
what do chromosomes control?
whether you're male or female
125
how many pairs of chromosomes in every human body cell?
23 matched pairs, in total 46 single chromosomes
126
what is labelled in the 23rd pair of chromosome?
XX or XY, they are the two chromosomes that decide whether you turn out male or female
127
what are the chromosomes males have (XX or XY)?
males have XY, the Y chromosome causes male characteristics
128
what are the chromosomes females have (XX or XY)?
males have XX, the XX combination causes female characteristics
129
why is the male reproductive system that at the end of the day determines the sex of the baby?
because all eggs have one X chromosome however the sperm can have either an X chromosome or a Y chromosome. So it really depends if the sperm that fertilised the egg carries an X or Y
130
why are all animals (including humans) bound to be slightly different from each other?
they are bound to be slightly different from each other because their genes are slightly different
131
what is the one exception of the rule of all of us having different set of genes?
identical twins, because their genes are exactly the same
132
what is most variations in animals caused by?
a mixture of genetic and environmental factors
133
what is almost every single aspect of a human (or other animal) affected by?
our environment, it can even have a large effect on human growth even before someone is born (ex. a baby's weight at birth can be affected by the mother's diet)
134
what are the 4 factors which aren't affected in any way by the environment?
- eye colour (important)
- hair colour in most animals (in humans, vanity plays a big part)
- inherited disorders like haemophilia, cystic fibrosis, etc.
- blood group (important)
135
what are three factors that can be influenced by both genes or environment?
- health
- intelligence
- sporting ability
136
what environmental factors strongly affect plants?
- sunlight
- moisture level
- temperature
- mineral content of the soil
(environmental variation in plants is much greater as you can see)
137
what is the theory of evolution?
life began as simple organisms from which more complex organisms evolved (rather than just popping into existence)
138
is the process of evolution still going on today?
yes, some bacteria are evolving to become resistant to antibiotics
139
what does natural selection mean?
the survival of the fittest. Over many generations the characteristics that increase survival becomes more common in the population, making the species become better and able to survive. The 'best' features are naturally selected and the species become more adapted to its enviroment
140
how did Charles Darwin come up with the theory of evolution?
he came up with the theory of evolution through natural selection
141
what does the survival of the fittest mean?
organisms with the most suitable characteristics for the environment would be more successful competitors and so would have a better chance of survival
142
what would a surviving organisms have an increased chance of?
of breeding and passing on their genes, meaning that a greater proportion of individuals in the next generation will have the better alleles, and so the characteristics, that help survival
143
how can bacterium become less affected by a particular antibiotic?
bacteria develop random mutation in their DNA. These can lead to changes in a bacterium's characteristics.
