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Biology > Topic 6 - Variation, evolution and inheritance > Flashcards

Topic 6 - Variation, evolution and inheritance Flashcards

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1
Q

What does sexual reproduction involve?

A

Fusion of male and female gametes - produced my meiosis.

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2
Q

What is the male and female gamete in humans?

A

Male - Sperm
Female - Egg

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3
Q

What is the male and female gamete in plants?

A

Male - Pollen
Female - Egg

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4
Q

What happens the the DNA in sexual reproduction?

A

Mixes DNA from each parent creating a variation in their offspring.

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5
Q

What is asexual reproduction carried out by?

A

All bacteria, some plants and few animals.

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6
Q

What is the difference between asexual reproduction and sexual reproduction?

A

No gametes only one parent cell.
No mixing of DNA so no variation in offspring.
Relies of mitosis instead of meiosis to produce genetically identical clones of parent.

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7
Q

What are the stages in meiosis

A

1) Before the cell starts to divide it duplicates in genetic information and become x shaped.
2) Then the parent cell divides once and half the number of chromosomes into two cells.
3) Then a second division occurs where each x shaped chromosome is split down the middle.
4) 4 genetically different haploid daughter cells are produced.

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8
Q

What are the differences between mitosis and meiosis?

A
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9
Q

What happens to the two haploid gametes during fertilisation?

A

The two haploid gametes (23 chromosomes each) fuse and the full number of chromosomes is restored to form a diploid zygote.

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10
Q

What are advantages and disadvantages of asexual reproduction?

A

Only one parent needed so fast and less energy needed.
No genetic variation in offspring so less likely to be able to survive environmental change.
Can produce many identical offspring when conditions are favourable.

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11
Q

What do genes code for?

A

A particular sequence of amino acids.

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12
Q

Define genome.

A

All the genetic material in an organism.

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13
Q

Why was the human genome project very important?

A

It has and will continue to improve our understanding of genes linked with different types of inherited disorders.

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14
Q

What is DNA and what is it made of?

A

DNA is a polymer made up of 2 strands of four different nucleotide monomers.

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15
Q

What decides the order of amino acids in a gene?

A

The order of bases.

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15
Q

What are the four different bases in DNA?

A

T
A
C
G

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16
Q

What are the two bases that always pair with each other and what is it called?

A

A and T
C and G
Complementary base pairing

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17
Q

What does mRNA do and how is it made?

A

Carries the code to the ribosome.
Made by copying code from DNA.

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18
Q

After the protein chain is formed what happens?

A

It folds to produce a unique shape. The shape is specific to its function as an enzyme, hormone or structural protein - are physically strong for example collagen.

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19
Q

What are mutations?

A

Changes to the DNA base sequence.
They occur continuously.
Rarely a mutation will code for an altered protein.

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20
Q

What is a gene?

A

A short section of DNA that codes for a protein.

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21
Q

Define a allele.

A

Different versions of a gene that give a certain characteristic.

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22
Q

What is a genotype?

A

The alleles an organism has for a particular gene

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23
Q

What is a phenotype?

A

The observable characteristics an organism has based on genotype.

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24
What are the three main types of genotypes?
Homozygous recessive Heterozygous Homozygous Dominant
25
What is homozygous recessive and how is it represented?
Both alleles in this genotype are recessive. It is represented by two lower case letters to represent alleles.
26
What is homozygous dominant and how is it represented?
Where both alleles are dominant alleles. It is shown in diagrams as 2 Capital letters.
27
What is heterozygous?
When there is one dominant and one recessive allele. It.
28
How is a dominant allele represented in a phenotype?
A dominant allele is always expressed in the phenotype if at least one copy is present in the genotype.
29
How is a recessive allele represented in a phenotype?
Recessive alleles need 2 copies to be expressed in the phenotype.
30
Do this punnet square and work out the percentage of a red flower.
75%
31
How are inherited diseases caused?
Caused by mutations in certain alleles which are then passed down from parents to offspring
32
How does cystic fibrosis work and who are the carriers?
Caused by a recessive allele. Need two copies of recessive allele to have the disorder. Heterozygous genotypes are carriers.
33
How does polydactyly work any carriers?
Gives you extra fingers/toes. Caused by a dominant allele. Only need one copy to have the disorder. No carriers as heterozygous have it.
34
What is embryo screening?
Embryo screening is a process used to check embryos for genetic disorders or genetic traits. It is used during in vitro fertilisation (IVF). A cell is removed from an early embryo. The DNA in that cell is tested for specific alleles that may cause genetic diseases (e.g. cystic fibrosis).
35
What are the advantages and disadvantages of embryo screening?
Advantages It will help to stop suffering. Treating disorders costs the government a lot of money. Disadvantages It implies people with genetic problems are undesirable this could increase prejudice. Screening is expensive.
36
Is a sperm allele XY or XX?
XY
37
What is variation?
Differences in characteristics between organisms.
38
How is genetic variation caused?
Random mutation
39
What is variation a result of?
Inherited genes Environment Combination of both
40
What is evolution?
Evolution is the change of inherited characteristics of a population over time and happens through the process of natural selection.
41
Define natural selection.
Where only some organisms with certain characteristics can survive and reproduce in their environment.
42
What did darwin state?
All species alive today evolved from simple life forms.
43
Describe the process of natural selection.
There is variation in the population due to random mutation. Some organisms have characteristics that enable them to survive and reproduce. They pass on alleles for their offspring so there are more in the population. This leads to populations having phenotypes that are best adapted to their environment. If this happens in two populations of the same species they can become so different in their phenotypes that they can no longer breed and produce fertile offspring therefore a new species formed.
44
What is selective breeding?
When humans artificially select plants and animals that are going to breed to obtain desirable characteristics.
45
What are the advantages and disadvantages and disadvantages of selective breeding
Advantages More yield Can improve disease resistance Disadvantages Reduces the gene pool (number of different alleles). This reduces the genetic variation so if a new disease appears all the stock closely related to it will die. Reduces biodiversity.
46
What is genetic engineering?
The transfer of a gene responsible for a desirable characteristic from one organism's genome to another.
47
How is genetic engineering carried out?§
A useful gene is identified (e.g. gene for insulin production). The gene is cut out using enzymes called restriction enzymes. The gene is inserted into a vector (usually a plasmid or virus). The vector is used to transfer the gene into target cells. The cells develop and reproduce with the new characteristic.
48
What are common used of Genetic enginnering?
Genetically modified crops Insulin production Medical research Gene therapy
49
What are advantages and disadvantages of genetic engineering?
Disadvantages They decrease biodiversity Potential long term effects of eating gm crops. Transplanted genes may get into the natural environment. Advantages Increase yield Can give nutrients to nutrient lacking countries. Gm crops are being used in some places often with no problem.
50
What are the two main ways to clone plants?
Tissue culture - few plant cells are put into growth medium and they grow into new plants. Cuttings - Take cutting from parent plant and them plant them to produce genetically identical copies.
51
What are benefits of tissue culture?
Allow scientists to preserve rare plants. They are made very quickly.
52
What is embryonic cloning
Embryonic cloning - Sperm cells are taken from a prize bull and and egg cells are taken from a prize cow. Then they are fertilised. The embryo that develops is split many times to form clones.
53
What did Lamarck find?
Found that characteristics changed during an organisms lifetime and that these were inherited. However this is not true.
54
What were 3 key observations Darwin made?
1) Organisms within a species vary in phenotype. 2) Some individuals with certain characteristics are more likely to survive. 3) Characteristics that enable survival are passed onto the next generation.
55
Why did not everyone agree with Darwin?
It was against religious beliefs. Not much other evidence to convince other scientists.
56
Define speciation.
The formation of two or more species from an original population due to isolation which prevents breeding from individuals in the population.
57
What are the stages in speciation?
1) Population becomes geographically isolated. 2) Isolation prevents breeding and mixing genes. 3) Random mutation occur this causes variation and changes in phenotypes. 4) Natural selection occurs due to different environments. 5) They change so much they can no longer interbreed.
58
What are the three ways fossils can form?
From preservation in places with no decay happening such as amber. Gradual replacement by minerals - hard parts such as bones are replaced by minerals. From casts and impressions
59
Why is the fossil record incomplete?
Many early life forms were soft bodied so all parts decayed. Many fossils have been destroyed by geological activity. Many fossils still undiscovered. Few fossils are made as conditions are rare.
60
What is extinction?
When there are no individuals left alive of the species.
61
What are factors that can cause extinctions.
New diseases New predators New competitors Changes to the environment Catastrophic events Humans causing extinction
62
How does antibiotic resistance occur?
Bacteria undergoes random mutation in their DNA. leading to changes in their characteristics such as antibiotic resistance. Since bacteria reproduce so rapidly they pass on there alleles to offspring.
63
What are ways to reduce antibiotic resistance?
Reduce prescriptions of antibiotics. Patients take full coarse of antibiotics every time. Reduce the use of antibiotics in farm animals.
64
List the order of classification and who was this developed by.
Kingdom Phylum Class Order Family Genus Species Developed by Carl Linnaeus.
65
How do you get the binomial species name?
Use the Genus and the species name.
66
Define species.
A group of similar organisms that can breed to produce fertile offspring.
67
What is the difference between archaea and bacteria?
Archaea = Ancient bacteria Bacteria = true bacteria e.g e.coli

Biology (9 decks)

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