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GCSE OCR Gateway Biology > B5 > Flashcards

B5 Flashcards

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1
Q

What is the genome?

A

The entire genetic material of an organism.

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2
Q

What is an allele?

A

Different versions of the same gene.

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3
Q

What can affect an organism’s phenotype?

A
  • genotype

- environmental conditions

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4
Q

Explain how your height can be affected by both your genome and the environment.

A
  • your genes control how tall you can grow

- your height also relies on your diet and sleeping hours

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5
Q

How do you classify the term ‘Discontinuous variation’ ?

A

Discontinuous variation is when there is only two or more distinct categories without intermediates. They aren’t affected by environmental factors.

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6
Q

How do you distinguish mitosis and meiosis?

A

Mitosis: formation of two identical daughter cells (asexual reproduction)
Meiosis: formation of four genetically non-identical cells (sexual reproduction)

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7
Q

Where does meiosis take place?

A

The reproductive organs (ovaries and testes) only.

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8
Q

How does meiosis introduce genetic variation?

A

Some of the father and the mother’s chromosomes go into each new cell when the cell divides. The mixing of chromosomes creates genetic variation.

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9
Q

Explain why gametes has to be haploid.

A

A male gamete fuses with a female gamete to form a fertilized egg during fertilization.
The gametes need to be haploid so the egg ends up with the diploid number of chromosomes and not twice as many.

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10
Q

What does it mean for the fertilized egg to be diploid?

A

It has the full set of chromosomes.

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11
Q

List features of sexual reproduction.

A
  • Cells divide by meiosis
  • offspring are non-identical
  • two parents
  • gametes fuse
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12
Q

Give two advantages of sexual reproduction.

A
  • genetic variation

- adaptation and evolution

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13
Q

What are the advantages and examples of asexual reproduction?

A
  • lots of offspring quickly > E. Coli (half an hour)

- only one parent needed (no mate needed) > aphids in the summer when there is plenty of food

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14
Q

Banana plants can produce asexually. Discuss the advantages and disadvantages of this form of reproduction.

A

Advantages: it can produce a lot of offspring very quickly without any mate
Disadvantage: no genetic variation > whole population can be affected if environment changes

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15
Q

Sperm and egg cells fuse during sexual reproduction. What’s the name of the resultant cell produced?

A

Zygote.

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16
Q

Name the three levels of organisation in a genome.

A

Chromosomes, DNA, genes

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17
Q

What do genes do?

A

Tell how a specific protein should be made.

18
Q

How many chromosomes does the human body contain?

A

46.

19
Q

What are nucleotides made up of?

A

Phosphate, sugar, base.

20
Q

What holds two strands of DNA together?

A

The attraction between bases.

21
Q

What is a dominant allele?

A

It is always expressed, regardless of the identity of the other allele.

22
Q

When are recessive alleles expressed?

A

If the other allele is also recessive.

23
Q

If the two alleles are different, we say that the person is:

A

Heterozygous (Bb).

24
Q

State the advantages and disadvantages that mutations can bring.

A

Advantages: Survival advantage
Disadvantage: Detrimental to protein function

25
Q

Explain the differences between coding and non-coding DNA.

A

Coding: affect proteins coded for by the gene, affect protein structure and the way it functions. (e.g active site of enzymes)
Non- coding: affects how genes are expressed (whether or not genes are ‘switched on’.)
They can stop the transcription of mRNA so the protein is not produced at all.

26
Q

What is cystic fibrosis caused by: a mutation in coding DNA or non-coding DNA?

A

Coding DNA.

27
Q

What is the purpose of genetic diagrams?

A

They help predict the phenotype of the offspring when you know the genotype of the parents.

28
Q

Explain how Punnett squares can be used.

A

Punnett squares are used to calculate the ratio of offspring phenotypes.

29
Q

The combination of chromosomes in a male are:

A

XY

30
Q

How can you identify if someone has cystic fibrosis?

A

If they have thick, sticky mucus building up in the lungs and digestive system.

31
Q

What research did Gregor Mendel publish about, that became the foundation of modern genetics?

A

Cross-breeding for height in pea plants.

32
Q

Describe the main difference between an artificial and a natural classification system.

A

Artificial: sorts organisms into groups depending on their observable features
Natural: Sorts organisms based on their evolutionary relationships/ common ancestors and structural features.

33
Q

Describe the hierarchy of natural classification systems in chronological order.

A

Kingdom, phylum, class, order, family, genus, species

34
Q

Define the term ‘Evolution’.

A

Evolution is the change in inherited characteristics of a population over time, through the process of natural selection.

35
Q

What does it mean by having an advantageous phenotype?

A

Some genetic variants give rise to characteristics that are better suited to a particular environment. These individuals will have a better chance of survival and have an increased chance of breeding and passing on their genes.

36
Q

Give two examples of mutations that give animals a survival advantage.

A

Alaskan wood frog: Freezes 60% of their body to survive cold weather
Camouflaged animals: Easier to survive in the wild without getting spotted
Komodo dragon: Dirty mouths to infect prey
Faster animals: Easier to catch prey

37
Q

Describe how fossils provide evidence for evolution.

A

They can show what organisms that lived in a long time ago looked like.
Arranging them in chronological order shows how organisms gradually changed.

38
Q

What theory did Charles Darwin come up with?

A

The theory of evolution by natural selection.

39
Q

Describe Wallace’s role in developing the theory of evolution by natural selection.

A

Observations by Wallace provided evidence to help support the theory.

40
Q

Explain how antibiotic-resistant bacteria provide evidence for evolution.

A

Answer in key points:

  • random mutations in DNA
  • leading to change in phenotype
  • it lives for longer and reproduces many more times.
41
Q

What are seedbanks and how do they work?

A

A method people have adapted to protect biodiversity.

Seeds are stored and replanted when they become extinct.

42
Q

How does the fossil record provide evidence for evolution?

A

It shows that many small changes can result in a large change in organisms over time.

GCSE OCR Gateway Biology (6 decks)

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