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AQA GCSE Biology > 4.6.1 reproduction > Flashcards

4.6.1 reproduction Flashcards

1
Q

A cell divides in a series of stages called

A

the cell cycle

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2
Q

What are the initial steps in the cell cycle?

A

The cell grows and organelle numbers increase, DNA replicates.

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3
Q

In the cell cycle after the DNA has replicated what happens next?

A

The copied chromosomes separate (mitosis) and then the cell divides into two.

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4
Q

What are the 2 forms of reproduction?

A

Asexual and sexual

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5
Q

Why is asexual reproduction important?

A

growth and repair

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6
Q

How many parents are involved in asexual reproduction?

A

1

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7
Q

How many parents are involved in sexual reproduction?

A

2

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8
Q

Which form of reproduction involves gametes?

A

sexual - fusion of egg and sperm

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9
Q

Which form of reproduction brings about variation?

A

sexual

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10
Q

Name an organism that reproduces asexually

A

bacteria, daffodil bulbs, strawberry tubers

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11
Q

Name an organism what reproduces sexually

A

humans

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12
Q

What form of cell division produces gametes?

A

Meiosis

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13
Q

Where does meiosis occur?

A

testes and ovaries

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14
Q

Where does mitosis occur?

A

in all body cells except testes and ovaries

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15
Q

In plants what are the sex cells?

A

pollen and egg cell

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16
Q

In animals what are the sex cells?

A

egg cell and sperm

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17
Q

What is another name for a gamete?

A

sex cell

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18
Q

Why does sexual reproduction bring about variation

A

Involves FUSION of egg and sperm, creating a unique combination of alleles

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19
Q

How many chromosome pairs are found in human body cells?

A

23 pairs

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20
Q

How many chromosomes are found in human sex cells

A

23

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21
Q

Chromosomes are found

A

in the nucleus

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22
Q

Chromosomes are made up from

A

DNA

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23
Q

Put the following in order of size starting with the smallest

cell, gene, nucleus, chromosome

A

gene, chromosome, nucleus, cell

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24
Q

What are genes?

A

Short sections on DNA found on chromosomes - they code for a particular characteristic

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25
How are mitosis and meiosis different?
Mitosis is used for growth and repair, meiosis makes gametes
26
How many times does the cell divide in meiosis?
twice
27
How are the cells produced different from the parent cell in meiosis
they have half the chromosome number
28
How many cells are produced at the end of meiosis?
4
29
How many cells are produced at the end of mitosis?
2
30
At fertilisation what happens to the chromosome number?
It doubles and chromosome number is restored.
31
In the first step in meiosis what has to happen?
DNA/chromosomes copy/replicate themselves
32
Are the cells produced at the end of meiosis genetically identical or genetically different?
genetically different
33
During fertilisation what happens?
egg and sperm cell fuse together
34
Following fertilisation, what cell is made?
Zygote (fertilised egg)
35
What happens to the the fertilsed egg made following fertilisation?
It will divide by mitosis, cell number will increase to form an embryo and then eventually a foetus
36
What makes an embyro and a foetus different?
A embryo contains unspecialised cells, a foetus contains cells that have begun to specialise - they have differentiated.
37
What does differentiation mean?
When cells (in an embryo) begin to specialise
38
Give an example of a specialised cell
muscle, red blood cell, nerve
39
What is the genome?
It describes all of the genetic material that an organism has
40
Describe the structure of DNA
Double helix
41
Where is your DNA found?
In the nucleus in the form of chromosomes
42
How are genes and proteins linked together?
genes (code for characteristics) code for a sequence of amino acids that make a protein
43
Why is studying the genome important?
Search and study genes that cause disease, then try and treat the disease
44
A DNA polymer is made up of...
repeating nucleotide units/monomers
45
Define phenotype
outward appearance
46
define genotype
combination of alleles
47
Where are proteins synthesised?
ribosomes
48
What types of jobs can proteins have?
enzymes, hormones, structural proteins e.g. collagen
49
Of the 23 pairs of chromosomes in a body cell, how many control characteristics only?
22
50
The 23 rd pair of chromosomes is called the sex chromosomes, what they in females and males?
females - XX | males XY
51
Name a genetic disorder that is inherited
cystic fibrosis or polydactyl
52
What is polydactyl?
Having extra digits
53
What is polydactyl caused by?
A dominant allele
54
What is cystic fibrosis?
A disorder of the cell membranes
55
What is cystic fibrosis caused by?
A recessive allele
56
Name characteristic caused by a SINGLE gene
tongue rolling, attached ear lobes
57
Name characteristics caused by MULTIPLE genes
eye colour, hair colour, height, nose shape
58
What is a dominant allele?
where only one copy of the allele is required to express that trait -this allele is always expressed if present
59
What is a recessive allele?
where two copies are required to express that trait, its not expressed in presence of a dominant allele
60
What does homozygous mean?
Where you have two copies of the SAME allele for a given characteristic e.g. BB, bb
61
What does heterozygous mean?
Where you have 2 different copies of an allele for a given characteristic e.g. Bb
62
What is an allele?
A different version of the same gene e.g. blue eyed allele, green eyed allele, brown eyed allele
63
What are enzymes?
Proteins that are biological catalysts
64
What are hormones?
Chemical messengers that travel in the blood stream to a target organ
65
Do gametes have one or two copies of each chromosome?
one
66
What are the chances of have a pregnant lady have a boy?
50%
67
What sex chromosome do you find in a sperm?
X or a Y
68
What sex chromosome do you find in an egg cell?
X only
69
What sex determines the sex of the child?
Father - you will always receive an X from mum and then X OR Y from dad
70
How could you determine whether a pregnant woman was carrying a child with a genetic disorder?
embryo screening
71
Why might people be against embryo screening?
its expensive, may lead to designer babies and all parents wanting to screen embryos and pick the most desirable
72
Why are people for embryo screening?
stops suffering treating disorders can be expensive there are laws to stop it going too far
73
chromosome combo for a girl?
XX
74
chromosome combo for a boy?
XY

AQA GCSE Biology (43 decks)

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