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AQA GCSE BIOLOGY > Inheritance, Variation, Evolution- REPRODUCTION > Flashcards

Inheritance, Variation, Evolution- REPRODUCTION Flashcards

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1
Q

What is sexual reproduction?

A

Sexual reproduction is the joining (fusion) of male and female gametes.

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2
Q

Describe the process in which gametes are made.

A

When a cell divides to form gametes:

  • copies of the genetic information are made
  • the cell divides twice to form four gametes,each with a single set of chromosomes

• all gametes are genetically different from each

other.

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3
Q

What is an embryo?

A

organism in the early stages of development.

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4
Q

What happens to cells as the embryo develops?

A

cells differentiate.

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5
Q

How is the DNA arranged in a prokaryotic cell?

A

Free in the cytoplasm as a nucleoid

And additional pieces of DNA are also found in bacteria in small loops called plasmids

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6
Q

Define the term gene

A

small section of DNA that codes for the sequence of amino acids that makes a specific protein

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7
Q

Define the term genome

A

entire set of genetic material that exists in a single organism

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8
Q

State the 3 main components of a nucleotide

A

Phosphate group
Sugar
Base

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9
Q

How many different types of base are found within DNA?

A

4

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10
Q

What are the 4 different types of base found in DNA nucleotides?

A

A, T, C and G

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11
Q

How do the nucleotide bases code for the production of proteins?

A

3 bases codes for one amino acid

So the sequence of bases codes for the sequence of amino acids that are linked together to make a protein

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12
Q

Which organelle is responsible for producing proteins?

A

Ribosomes

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13
Q

How are proteins made? Hint: 5 steps

A

The instructions in the gene are copied into a messenger molecule called mRNA
The mRNA leaves the nucleus and travels to the cytoplasm
Ribosomes attach to the mRNA
Carrier molecules carry amino acids to the ribosome The ribosome joins the amino acids together in the sequence that is determined by the mRNA

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14
Q

After the amino acids are joined together in a long chain, what must happen before the protein can carry out it’s function?

A

When the protein chain is complete it folds up to form a unique shape.
This unique shape enables the proteins to do their function

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15
Q

Define the term mutation

A

change to the sequence of DNA bases

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16
Q

State the 3 different types of mutation

A

Insertion
Deletion
Substitution

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17
Q

Describe an insertion mutation

A

A new additional base is inserted into the DNA
This alters how triplets of DNA bases are ‘read’
Each triplet will change at the point after the insertion

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18
Q

Describe a deletion mutation

A

A nucleotide base is deleted from the DNA
This will alter how the triplets of DNA bases are ‘read’
Each triplet will change at the point after the insertion
This is described as a frameshift mutation

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19
Q

Describe a substitution

A

A nucleotide base in the DNA sequence is changed to a different nucleotide base
This may alter which amino acid is inserted into the sequence

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20
Q

Name the two types of reproduction

A

Asexual reproduction

Sexual reproduction

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21
Q

give the characteristics of asexual reproduction

A

involves only one parent

no fusion of gametes

no mixing of genetic information

leads to genetically identical offspring (clones)

Only mitosis is involved

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22
Q

give the characteristics of sexual reproduction

A

involves two parents

involves the mixing of genetic information

leads to variety in the offspring

involves meiosis

It involves the fusing of gametes

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23
Q

State the 2 types of gametes that are involved in sexual reproduction in flowering plants

A

pollen

egg cells

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24
Q

Give 3 advantages of sexual reproduction

A

Produces variation in the offspring

If the environment changes variation gives a survival advantage by natural selection

Natural selection can be speeded up by humans in selective breeding to increase food production

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25
Q

Give 4 advantages of asexual reproduction

A

Only one parent needed
More time and energy efficient as do not need to find a mate
Faster than sexual reproduction
Many identical offspring can be produced when conditions are favourable

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26
Q

Name 3 organisms that reproduce by both asexual and sexual reproduction depending on the circumstances

A

Malarial parasites
Fungi
Plants e.g. strawberry plants

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27
Q

State the term that describes the fusing of two gametes to form a zygote

A

Fertilisation

28
Q

How many chromosomes are found in a gamete?

A

Half the full number i.e. haploid (n)

For human cells this is 23

29
Q

Explain why sexual reproduction causes greater genetic variation in the offspring

A

Sexual reproduction involves the fusing of two gametes
Each gamete contains genetic material from each parent
The zygote will have half the DNA from the mother and half from the father
This mixture of genetic information produces variation

30
Q

State the 3 main stages of mitosis

A

Copies of the genetic information are made
The cell divides once to form two daughter cells, each with a full set of chromosomes(2n)
All gametes are genetically identical to each other.

31
Q

State the 3 main stages of meiosis

A

Copies of the genetic information are made
The cell divides twice to form four gametes, each with a single set of chromosomes
All gametes are genetically different from each other

32
Q

Define the term heterozygous

A

The individual has a genotype that has 2 alleles that are different (one dominant and one recessive)

33
Q

Define the term homozygous

A

The individual has a genotype that has 2 alleles that are same

34
Q

Define the term allele

A

A variety of a gene

35
Q

Define a dominant allele

A

An allele that is expressed in an individual irrespective if there is another dominant allele OR a recessive allele present

36
Q

Define a recessive allele

A

An allele that is only expressed in the absence of a dominant allele and the presence of a second recessive allele

37
Q

Define the term phenotype

A

physical characteristic expressed by an individual due to the genotype they have
Most characteristics are a result of multiple genes interacting, rather than a single gene

38
Q

Name a disease caused by a recessive allele

A

Cystic fibrosis

39
Q

Describe 2 symptoms of cystic fibrosis

A
  • production of excess mucus

- sticky mucus

40
Q

Name a disease caused by a dominant allele

A

Polydactyly

41
Q

How can genetic disorders be detected in individuals?

A

Embryo screening

42
Q

Describe the general shape of a DNA molecule

A

A double helix

43
Q

DNA is a polymer. What are the monomers that are linked other to form DNA called?

A

Nucleotides

44
Q

Why has the study of the Human genome been useful for scientists?

A

Gained an understanding of how some diseases are inherited
Used this understanding of inheritance to develop effective treatments
Used the genome to determine historical migration patterns of certain groups of people

45
Q

What type of molecule is DNA?

A

Polymer

46
Q

Some parts of the DNA do not code for specific proteins. What is the role/function of these parts of the chromosome?

A

To control if the genes are expressed

Which determines if the proteins are actually produced

47
Q

give 3 functions of proteins

A
  • enzymes- act as biological catalysts
  • hormones- used to carry messages around body
  • structural role- physically strong
48
Q

How does a change in DNA bases cause a change in the protein structure and function?

A
  • could lose strength if shape is changed

- making them useless in providing support and structure

49
Q

Suggest how mutations may cause a change in enzyme activity

A
  • mutation causes amino acid sequence to change
  • this causes shape of active site to change
  • so substrate no longer binds to active site
50
Q

State how malarial parasites demonstrate both sexual and asexual reproduction

A

Malarial parasites reproduce asexually in the human host

but sexually in the mosquito

51
Q

State how fungi demonstrate both sexual and asexual reproduction

A

Many fungi reproduce asexually by spores

They also reproduce sexually by spores to give variation

52
Q

Explain why it is an advantage for fungi to be able to produce spores asexually and sexually

A

fungi can produce spores asexually to make many identical spores in a short period of time

fungi can produce spores sexually to make genetically different spores to increase chances of surviving environmental conditions

53
Q

State how some plants demonstrate both sexual and asexual reproduction

A

Flowering plants produce seeds sexually

reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils

54
Q

State the type of cell division involved in asexual reproduction

A

Mitosis

55
Q

State the type of cell division involved in sexual reproduction

A

Meiosis

56
Q

Which type of reproduction involves the production of haploid gametes

A

Meiosis

57
Q

How many chromosomes are found in a gamete?

A

Half the full number i.e. haploid (n)

For human cells this is 23

58
Q

How many chromosomes are found in a somatic (body) cell?

A

A full set of chromosomes i.e. diploid (2n)

For human cells this is 46

59
Q

Explain why sexual reproduction causes greater genetic variation in the offspring

A
  • involves the fusing of two gametes
  • Each gamete contains genetic material from each parent
  • zygote will have half the DNA from the mother and half from the father
  • mixture of genetic information produces variation
60
Q

State the 4 advantages of sexual reproduction

A

It increases genetic variation

Genetic variation increases chances of survival of species if there is a change in the environment

variation increases chances of surviving change in environment and breed and pass the successful alleles on to the next generation (called natural selection)
Scientists can use selective breeding to speed up natural selection

61
Q

State the 5 advantages of asexual reproduction

A

Only one parent is required (so there is no need to find a mate)
This means asexual reproduction uses less energy (no energy used in finding a mate, producing gametes)
It is also faster (as no time is used in finding a mate)
Many genetically identical offspring can be produced when conditions are favourable
It maintains genetic stability by producing genetically identical cells

62
Q

State which part of the cell is affected by cystic fibrosis

A

It is a disorder of the cell membranes

63
Q

State 2 situations when embryo screening can take place

A

During IVF – prior to implanting the embryo in the female’s uterus

After the female has conceived: cell can be removed from the developing embryo and analysed in the lab

64
Q

Give 3 reasons why some people are in favour of carrying out embryo screening

A
  • it will help stop ppl suffering
  • treating disorders costs government lots of money
  • laws that prevent technology going too far
65
Q

Give 3 ethical concerns some people may have about embryo screening

A
  • implies ppl with genetic problems are ‘undesirable’- could increase predjudice
  • screening = expensive
  • could come a point where everyone wants to screen embryos

AQA GCSE BIOLOGY (4 decks)

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