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Biology > Inheritance, Variation and Evolution > Flashcards

Inheritance, Variation and Evolution Flashcards

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1
Q

What is asexual reproduction? What does this produce? Why? - IVE

A

Asexual production is the production of offspring with 1 parent. Produces an IDENTICAL CLONE as genetic material doesn’t mix

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2
Q

What process of cell division does asexual reproduction use? - IVE

A

Mitosis -
Chromosomes in a nucleus are copied, chromosomes and chromatids are moved towards poles. Chromosomes separate and cell divides into 2 identical daughter cells

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3
Q

What are cells that are produced by mitosis used for? - IVE

A

Growth of tissues
Repair of damaged tissues
Replacement of worn out cells

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4
Q

What is asexual reproduction?

A

Reproduction to produce offspring involving the fusion of gametes to form a zygote

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5
Q

What percentage of a zygote’s chromosomes does each gamete contain? - IVE

A

50%

When they combine they form a full set of chromosomes

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6
Q

What type of cell division creates GAMETES ONLY? - IVE

A

Meiosis

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7
Q

Describe the process of meiosis cell division. How many cells does meiosis produce? - IVE

A

In each cell there are 4 chromosomes, which duplicate to form 8 individual chromosomes, with the pairs lining up, genetic information swapping between chromosomes and the cell dividing twice. Produces 4 CELLS

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8
Q

Name 2 advantages and disadvantages each of sexual reproduction - IVE

A

+ve: creates variation in offspring, disease less likely to affect all people, species can adapt to new environments
-ve: time and energy needed to find a mate, not possible for isolated individuals

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9
Q

Name 2 advantages and disadvantages each of asexual reproduction - IVE

A

+ve: Population can increase rapidly, only 1 parent needed, faster than sexual reproduction, time and energy efficient
-ve: doesn’t lead to variation in a population, disease may affect all individuals, may only be suited to 1 habitat

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10
Q

What is DNA? What is a chromosome? - IVE

A

DNA is in double helix shape, carrying genetics, determines characteristics
Chromosomes are long threads or DNA made up of genes

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11
Q

What are genes? What do they do? - IVE

A

A small section of DNA. Each gene codes a sequence of amino acids to make a protein. This is what is passed on to offspring

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12
Q

What is the (entire human) genome? What does this enable us to do? - IVE

A

The complete set of DNA found in an organism (all humans)

Enables us to search for genes linked to different diseases, understand inherited diseases and treatment

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13
Q

Describe the structure of DNA (mention backbone, links between) - IVE

A

Constructed of a double helix backbone, supported by links between a pair of nucleotides (A-T OR C-G) made from sugar and phosphate sections

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14
Q

What are base pairs and what are the 4 specific base pairs? - IVE

A

Base pairs are chemical cross links between the 2 strands of DNA
(Adenine, Thymine), (Cytosine, Guanine)

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15
Q

How do ribosomes know which specific proteins to synthesise? - IVE

A

A copy of the DNA code for the protein is released from the nucleus, called mRNA, which enters the ribosome and synthesises a specific protein based on the code.

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16
Q

What are mutations? Can they be inherited? - IVE

A

A change in a gene or chromosome. A rare, random change in genetic material
Can be inherited

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17
Q

What can cause mutations? - IVE

A

Spontaneous mutations
Ionising radiation
Chemical mutagens (tar in cigarette smoke)

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18
Q

What are 1. substitution and 2. insertion mutations? - IVE

A
  1. A specific base is substituted with another base, meaning a different amino acid is synthesised
  2. An extra base is inserted between bases, and a different protein is synthesised
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19
Q

What are 1. deletion and 2. inversion mutations? - IVE

A
  1. A base is removed between bases and results in a different protein being synthesised
  2. A base changes order, resulting in a different amino acid, and maybe protein, being made
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20
Q

How many nucleotides makes up a specific reading for 1 amino acid? - IVE

A

A specific amino acid is made of 3 nucleotides, as they are read this way when entering a ribosome. This is called a triplet code

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21
Q

What is fertilisation? Explain this in terms of human chromosomes - IVE

A

The fusion of the nuclei of male and female gametes, in humans each with 23 chromosomes to provide the total number of 46 for a human body

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22
Q

What are gametes? What are the human gametes? - IVE

A

Sex cells. The human sex cells are sperm and eggs (ovums)

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23
Q

What are alleles? Name an example - IVE

A

Different versions of the same gene, for example eye colours (blue allele, brown allele)

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24
Q

What are a genotype and a phenotype? - IVE

A

Genotype are the alleles that an organism has for a particular characteristic. These alleles are expressed as the phenotype, the visible characteristics of an organism as a result of genes

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25
Q

What are dominant and recessive alleles? (Are they expressed, how are they represented) - IVE

A

Dominant - always expressed even if 1 allele is present, represented by a capital letter
Recessive - only expresses if 2 of these alleles are present. Represented by a lower case letter

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26
Q

What are homozygous and heterozygous alleles? - IVE

A

Homozygous - alleles are identical for each characteristic (AA/aa)
Heterozygous - alleles are different for each characteristic (Aa)

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27
Q

How do you construct punnett squares? - IVE

A

Discover the parental genotypes. Split them into single alleles (DOM in CAPS, recess in lower) and add around edges of Punnett square. Combine in each box and calculate probabilities of each outcome

28
Q

What determines the biological sex of a human? - IVE

A

Males have XY chromosomes (heterozygous), females have XX chromosomes (homozygous)

29
Q

What are the effects of cystic fibrosis? Is it caused by a faulty dominant or recessive allele? What does this mean? - IVE

A

Cystic fibrosis is a disorder which clogs the lungs with thick mucus which damages them
Caused by recessive allele, meaning that only homozygous recessive alleles display the trait

30
Q

What are the effects of polydactyly? Is it caused by a faulty dominant or recessive allele? What does this mean? - IVE

A

Polydactyly is a condition causing someone to have extra fingers or toes. Caused by a dominant allele, meaning if you have the dominant allele, you expressed this trait

31
Q

Describe the steps of gene therapy - IVE

A

A faulty gene is identified, enzymes used to cut out normal allele from donor. These alleles are copied and inserted into the cells of a person with a mutation or faulty gene

32
Q

What problems are there with gene therapy? - IVE

A

Alleles may not be inserted into every target cell, may not be inserted into the right place in chromosomes

33
Q

What is pedigree analysis? - IVE

A

Pedigree analysis is the use of data on family history of genetic disorders to predict whether family members will inherit a disease

34
Q

What did Mendel discover? How did he do this? - IVE

A

Mendel discovered that if you breed red flowered pea plants with white, all offspring had red flowers. Of the offspring that were bred, some had red flowers, some had white

35
Q

How can we apply our modern understanding to Mendel’s discoveries? (In terms of Alleles) - IVE

A

We now know that one gene (RED) was dominant, whilst white was recessive

36
Q

Why was Mendel’s work not accepted by most scientists at the time? - IVE

A

When he presented his work he didn’t fully understand it, his work was not published widely, couldn’t explain the science behind it

37
Q

What is variation? - IVE

A

Variation is the process by which members of a species are not identical

38
Q

What is genetic variation? Give human examples - IVE

A

Variation due to the combination of 23 chromosomes from each parent in fertilisation
Blood group, skin colour, eye colour, sex

39
Q

What is environmental variation? Give examples in humans - IVE

A

Characteristics that can be affected by diet, lifestyle, culture, accidents
Scars, language and accent, weight

40
Q

How can mutations lead to a rapid change in a species? - IVE

A

If a mutation is displayed in the phenotype and it is of benefit to the organism in a specific environment, then it can lead to the advancement of a species when passed on

41
Q

What is Natural Selection? - IVE

A

A process where organisms that are better suited to an environment will survive and have more offspring and pass these traits on to offspring (Survival of the Fittest)

42
Q

Which scientist discovered the idea of natural selection, an example of which is the peppered moth - IVE

A

Charles Darwin came up with the Theory of Evolution.
In 19th century, pollution made bark on trees become darker. Light coloured moths weren’t camouflaged and were eaten. Dark moths were and passed this trait onto offspring

43
Q

What is selective breeding? What examples are there of this? (animal and plant)- IVE

A

Where humans breed plants/animals to produce desired characteristics
Breeding Cows that produce lots of milk
Breeding disease resistant wheat plants

44
Q

What are the benefits and risks of selective breeding? - IVE

A

+ves: new varieties can produce high yields of a product, animals can be bred that don’t cause harm (cows without horns)
-ves: reduced genetic variation can lead to attack by diseases, can create physical problems unknowingly

45
Q

What is genetic modification? - IVE

A

A process which artificially transfers genetic information from one donor cell to another organism(s)

46
Q

What are the steps of genetic modification? - IVE

A

Identification of the desired trait, of which the gene responsible for this is cut out of the chromosome with an enzyme. The gene is transferred into a plasmid from a bacterial cell, and then into a bacterial cell where it can rapidly reproduce

47
Q

What is currently done to improve crop yields/human life using genetic modification? - IVE

A

Produce human insulin for type 1 diabetics
Make herbicide resistant crops that can tolerate the herbicide
Make ‘golden rice’ which helps improve human vitamin A production

48
Q

What risks and benefits are there of genetic modification? - IVE

A

+ve: faster and more efficient than selective breeding, improves crop yields or quality, makes herbicide resistance
-ve: transfer of genes may cause widespread harm, not ethical to interfere with nature, can cause allergic reactions

49
Q

How can plants be cloned by cuttings? - IVE

A

A branch from a parent plant is cut off with lower leaves removed and the stem placed in compost. Plant hormones used to develop. After a few weeks a clone plant grows

50
Q

How can plants be cloned through tissue culture? How is this better/worse than taking cuttings? - IVE

A

Small pieces of plants are grown in vitro using agar jelly with hormones and nutrients.
More expensive than taking cuttings but can preserve rare species or grow on a large scale

51
Q

How are embryo transplants performed in animals? Do they produce unique or identical offspring? - IVE

A

Sperm from a bull from high dairy yield herd artificially inseminates a cow. Zygotes develop into embryos and are harvested. These embryos are split into smaller embryos and transplanted into host mothers. IDENTICAL.

52
Q

How is adult cell cloning performed? Does this produce unique or identical offspring? - IVE

A

An unfertilised egg cell (without nucleus) is combined with the nucleus of a body cell to have full set of chromosomes. Given an electric shock to stimulate cell division. When the embryo is a ball of cells it is implanted into womb. Identical to body cell sheep

53
Q

How does evolution by natural selection work? - IVE

A

As an environment changes, individuals with certain traits are more suited to it and more likely to survive to pass these traits onto offspring. This leads to gradual evolution, as those without useful traits die out

54
Q

What was Lamarck’s theory of evolution? What supposed example is there of this? Was this theory correct? - IVE

A

A characteristic that is used more by an organism becomes enhanced and one that isn’t disappears. Any improved features are passed to offspring. An example is a giraffe’s long neck, used to reach tall trees. This idea was WRONG

55
Q

What was Darwin’s proposed theory of evolution? - IVE

A

Individual organisms have traits more suited to an environment which means they are more likely to breed successfully. These traits are passed onto offspring, meaning a species gradually evolves

56
Q

What problems were there with Darwin’s proposed theory of evolution? - IVE

A

The theory challenged religious ideas that God made all animals and plants (creationism), insufficient evidence for Darwin’s case, not proven for 50 years after publication

57
Q

What is Alfred Wallace known for contributing towards the idea of evolution? - IVE

A

The idea of speciation, the formation of new and distinct species in evolution

58
Q

What are fossils? What can they be made in? - IVE

A

The preserved remains of a dead organism from millions of years ago.
Preserved in amber, peat bogs, tar, ice, rock

59
Q

How do fossils support Darwin’s theory of evolution? - IVE

A

Fossils show the most basic, old organisms and more developed organisms, which show the evolution of species

60
Q

Why are there gaps in the fossil record? - IVE

A

Many soft-bodied forms of life have been destroyed be geological activity like volcanic eruptions or earthquakes

61
Q

What is antibacterial resistance? How is this an example of evolution? - IVE

A

Random mutations occur in the genes of bacterial cells, which protect the cell from antibiotics. Bacteria without the mutation die from antibiotics, but the resistant strain can reproduce and evolve

62
Q

What is a specific example of antibiotic resistant bacteria? How can antibiotic resistance be prevented? - IVE

A

MRSA
Doctors should not inappropriately prescribe antibiotics where they aren’t needed, patients should always complete a full course of antibiotics to ensure all bacteria are killed

63
Q

What is extinction, and what can cause it to occur? - IVE

A

Extinction is when an entire species is wiped out

Caused by new diseases, new predators, new competitors, changes to an environment or a catastrophic geological event

64
Q

What is the Linnaean system of classification? What mnemonic helps remember this? - IVE

A

Kingdom, Phylum, Class, Order, Family, Genus, Species

KIDS PREFER CANDY OVER FRESH GREEN SALAD

65
Q

What is the binomial system of naming species? Why is this important to scientists? - IVE

A

Genus + Species

Allows scientists to classify species accurately and individually

66
Q

What is Carl Woese’s 3 domain system? (Name the 3 domains and their components) - IVE

A

Archaea - primitive bacteria usually living in extreme environments
Bacteria - true bacteria
Eukaryota - protists, fungi, plants and animals

Biology (7 decks)

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