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gcse biology > b13 - reproduction > Flashcards

b13 - reproduction Flashcards

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1
Q

define allele

A
  • a form or version of a gene
  • you have two copies of each gene, one from each parent and these are alleles
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2
Q

define asexual reproduction

A
  • does not involve fusion of gametes
  • all information comes from one parent
  • little variation
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3
Q

define sexual reproduction

A
  • invoes fusion of gametes
  • mixing of genetic information so more variation
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4
Q

how are gametes formed?

A

by meiosis
- this process produces gametes (chromosome number halved)

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5
Q

what happens when 2 gametes fuse?

A

fertilisation, a zygote is made and full chromosome number restored

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6
Q

what are the sex cells in animals?

A

egg cells and sperm

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7
Q

what are the sex cells in plants?

A

egg cells and pollen

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8
Q

what happens during meiosis?

A

1) genetic material copied, chromosomes double
2) cell divides twice to form 4 gametes with single set of chromosomes
- all gametes are genetically different from eachother and from the parent cell

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9
Q

how does mitosis link to meiosis?

A

once gametes (made from meiosis) fuse together, a new individual develops as this cell repeatedly divides by mitosis

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10
Q

give 4 advantages of asexual reproduction

A
  • only one parent needed
  • more time and energy efficient
  • faster than meiosis
  • identical offspring produced
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11
Q

give 2 disadvantages of asexual reproduction

A
  • little variation
  • all offspring are affected if environmental conditions change
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12
Q

give 3 advantages of sexual reproduction

A
  • variation
  • if environment changes, variation given a survival advantage by natural selection
  • natural selection can be accelerated by humans in selective breeding to increase food production
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13
Q

disadvantages of sexual reproduction

A
  • two gametes/ parents needed
  • takes time, energy to find mate/spread gametes
  • often slower than asexual reproduction
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14
Q

give 3 organisms that reproduce using both methods

A

1) malarial parasites
2) fungi
3) flowering plants

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15
Q

what is genetic material made up of?

A

deoxyribonucleic acid (DNA)

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16
Q

define the structure of the DNA

A
  • polymer (long molecule)
  • double helix structure
17
Q

where is DNA found?

A

chromosomes

18
Q

define a gene

A

small section of DNA on chromosome

19
Q

define ‘genome of an organism’

A

entire genetic material of that organism

20
Q

why is it helpful to know the human genome?

A
  • helps search for genes linking to differenct types of disease
  • helps understand and treat inherited disorders
  • helps trace human migration
21
Q

what are the long strands of DNA made up of?

A

chains of alternating sugar and phosphate sections

22
Q

what is attatched to the sugar in DNA?

A

one of four bases: A, C, G or T

23
Q

what makes up a nucleotide molecule?

A

a sugar, a phosphate, a base

24
Q

what does the order of bases control?

A

controls order in which amino acids are joined together to form a particular protein

25
Q

define mutation

A

a change in the order of bases that causes the wrong protein to be made

26
Q

what is base C always linked to?

A

base G

27
Q

what is base T always linked to?

A

base A

28
Q

what happens during protein synthesis?

A

1) gene produces a protein template
2) template leaves nucleus through pore in membrane
3) template attaches to ribosome in cytoplasm
4) carrier molecules in cytoplasm carry a specific amino acid
5) carrier molecules attatch themselves to template in order defined by template
6) the amino acids they carry join together to form protein
7) protein chain detaches from carrier molecules and folds into specific shape
8) carrier molecules return to cytoplasm and pick up more amino acids

29
Q

define ‘gene expression’

A

when a gene codes for a protein that is synthesised in cell, gene is expressed

30
Q

what does DNA do?

A
  • part of it codes
  • non-coding part are involved in switching genes on and off
31
Q

how can expression of genes be affected?

A

variations in non-coding areas of DNA

32
Q
A

gcse biology (17 decks)

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