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Biology Paper 2 > Inheritance, Variation And Evolution > Flashcards

Inheritance, Variation And Evolution Flashcards

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1
Q

What is DNA?

A
  • chemical that genetic material in a cell is made from
  • contains coded information
  • determines inherited characteristics in an organism
  • found in the nucleus of animal and plant cells in long structures called chromosomes
  • it is a polymer made up of two strands coiled together in the shape of a double helix
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2
Q

What is a gene?

A
  • a small section of DNA found on a chromosome
  • each gene coded for a particular sequence of amino acids which make a specific protein
  • genes tell cells what order to put the amino acids together
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3
Q

What is a genome?

A

An entire set of genetic material in an organism

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4
Q

What is sexual reproduction?

A

The fusion of the male and female gametes to produce offspring which are genetically different to either parent. Each gamete contains 23 chromosomes meaning that the offspring inherits 46 chromosomes (diploid cell)

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5
Q

What is asexual reproduction?

A

There is only one parent and so there is NO fusion of gametes so the offspring are genetically identical to the parent. It happens by mitosis.

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6
Q

Which chromosomes decide your sexuality?

A

The 23rd pair labelled XX or XY.
XX- girl
XY-boy
50% for each sex, dependent on the male

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7
Q

What is a genotype?

A

The combination of alleles you have

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8
Q

What is a phenotype?

A

The characteristics you have

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9
Q

What is a recessive allele?

A

cc or dd (homozygous recessive)

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10
Q

What is a dominant allele?

A

Rr or RR (can be homozygous or hetrozygous)

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11
Q

What is cystic fibrosis?

A

A genetic disorder of the cell membranes which results in body producing a lot of thick sticky mucus in the air passages of the pancreas

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12
Q

How is cystic fibrosis caused?

A

Caused by a recessive allele (ff) both parents must be carriers or have the disorder themselves

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13
Q

What is polydactyl?

A

Genetic disorders where a baby’s born with extra fingers or toes

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14
Q

How is polydactyl caused?

A

Caused by a dominant allele (D) so can be inherited if one person carries the defective allele, and they will have the condition too

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15
Q

Advantages of embryonic screening?

A
  • will help people stop suffering
  • treating disorders costs government a lot of money
  • laws to stop it going too far
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16
Q

Disadvantages of embryonic screening?

A
  • it implies people with genetic problems are ‘undesirable’ which causes prejudice
  • everyone wants to screen embryos to pick the most ‘desirable one’
  • it is expensive
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17
Q

What was the contribution of Mendel?

A
  • characteristics in plants are determined by ‘hereditary units’
  • offspring receives one unit from each parent
  • hereditary units can be dominant or recessive, dominant one takes over
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18
Q

How is genetic variation caused?

A

(Sexual reproduction)

  • Genes are passed on in the gametes which the offspring develop
  • The combining of genes from two parents causes genetic variation
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19
Q

What is a mutation?

A

A change to a sequence of bases in DNA, which leads to the changes of a protein a gene codes for

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20
Q

What is the theory of evolution?

A

All of today’s species have evolved from simple life forms that first started to develop billions of years ago

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21
Q

What were the ideas of Charles Darwin?

A
  • organisms with the most suitable characteristics for environment would be most likely to survive ‘survival of the fittest’
  • organisms that survive are most likely to reproduce and pas on the genes to their offspring m
  • over time, beneficial characteristics become more common in the population, it evolves
22
Q

What is speciation?

A

When the phenotype of organisms changes so much because of natural selection that a new species is formed so they don’t become reproductively isolated.

23
Q

Why does extinction happen?

A
  • environmental changes (destruction)
  • new predator kills them all
  • a new disease wipes them all out
  • they can’t compete with another species for food
  • catastrophic event occurs
24
Q

Why didn’t everyone believe Darwin’s ideas?

A
  • went against religious beliefs about how life on Earth developed
  • wasn’t enough evidence to convince scientists
25
Q

What were Lamarck’s ideas?

A

He thought that if a characteristic was used a lot by an organism, it would become more developed during its lifetime and the offspring would inherit this

26
Q

What is selective breeding?

A

When you select the organisms that have the desired characteristics you’re after and breed them together. Then select the best of the offspring and breed them together. Continue this process until generations have the desirable trait until all the offspring have this characteristic

27
Q

What is a problem with selective breeding?

A

They are all susceptible to the same diseases which may wipe them all out

28
Q

What is genetic engineering?

A
  • useful gene is cut from an organisms genome using enzymes and is inserted into a vector
  • the vector is a virus
  • the useful gene is inserted into its cells
29
Q

How many chromosomes does a gamete (sex cell) contain?

A

23 chromosomes

30
Q

Adamant ages of sexual reproduction?

A
  • natural process
  • variation in offspring
  • less risk of death
  • encourages evolution
  • natural selection gives survival advantage
31
Q

What are advantages of genetic engineering?

A
  • crops produce more, better fruit and make them resistant to disease and herbicides
  • increases the yield of food
32
Q

What is a diploid?

A

A full set of chromosomes (46)

33
Q

Advantages of asexual reproduction?

A
  • more time and energy efficient
  • faster than sexual reproduction
  • identical offspring can be produced
34
Q

What is a haploid?

A

Half a set of chromosomes (23)

35
Q

What is found in a DNA strand?

A
  • phosphate group
  • sugar
  • base
  • nucleotide
36
Q

Which bases go together?

A

A –> T

C –> G

37
Q

What is a carrier?

A

When a disease is caused by a recessive allele and a person carries both the dominant and recessive (Ff)
They do not need to carry the disorder themselves

38
Q

What is genetic variation?

A

Caused by the confining of the genes from two parents.

  • eye colour
  • blood group
  • inherited disorders
  • gender
39
Q

What is a fossil?

A

Remains of an organism from thousands of years ago which tell us how a species have evolved over time

40
Q

What is environmental variation?

A

The conditions that organisms live and grow in.

  • scars
  • weight
  • teeth condition
  • skin colour
  • academic
41
Q

How are fossils formed?

A

When an organism is buried in a soft material such as clay. The clay hardens around it and the organism decays, leaving a cast of itself

42
Q

What is natural selection?

A

The process where organisms better adapted to the environment tend to survive and produce more offspring

43
Q

Examples of GM crops?

A

GM insulin
Golden rice
Herbicide resistant crop plants

44
Q

Why is GM insulin better than insulin taken from pigs and cows?

A
  • easier to create high quantities of insulin
  • less likely to cause an adverse reaction
  • overcomes ethical concerns from vegetarians and others
45
Q

What happens in adult cell cloning?

A
  • nucleus is removed from an unfertilised egg cell
  • injected into the empty body cell
  • an electric shock is applied to make the egg cell begin to divide to form an embryo
  • while it is still a ball of cells, it is inserted into the womb of an adult female
  • the embryo continues to grow and develop
46
Q

What is MRSA?

A

It is very dangerous because it is resistant to most antibiotics.
-example of natural selection as over time it has become resistant to antibiotics

47
Q

How can we reduce the development of antibiotic resistant strains?

A
  • always avoid unnecessary use of antibiotics

- always complete the full course set

48
Q

What is the binomial system responsible for?

A

The binomial system names an organism using its genus and species.

49
Q

What is protein synthesis?

A
  • sugar&phosphate molecules form a ‘back bone’ to DNA strands
  • one of the four bases (ACGT) joins to each sugar
  • each base links to a base on opposite strand in the helix
  • complementary base pairing occurs (A&T and (C&G)
50
Q

What is the role of mRNA?

A

Acts as a messenger between the DNA and ribosome- carries code between the two

Biology Paper 2 (3 decks)

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