B14 - Variation & Evolution 2️⃣✅

Question 1

Why do populations have genetic variation ?

Answer 1

Because of sexual reproduciton and random fusion of gametes, random swapping of alleles in meiosis and random spontainious mutations

Question 2

What are the 3 types of variation?

Answer 2

Genetic variation e.g. eye colour, ear shape
Environmental variation e.g. hair length, peirced ears
Both - sometimes the environment can affect the gene expression e.g. height, weight, hair colour

Question 3

What type of data is genetic variation?

Answer 3

Categoric - you either inherit the gene or you dont, no inbetween e.g. male or female

Question 4

What type of data is envrionmental variation?

Answer 4

Contiunous - not just tall or short, vaules inbetween, very varied

Question 5

What is natural selection?

Answer 5

Natural selection is a mechanism of evolution. Organisms that have characteristics suited more to their environment are more likely to survive and pass on the genes that aided their success causing the alleles that have enabled the survivial are then passed onto the next generation

Question 6

How do variations in species come to be?

Answer 6

Variants arise from mutations - mutations happen very frequently and usually have no affect on the pheontype of an organism, rarely causes harm to an organism and very rarley causes an adaptation that makes an organism better suited to its environment/ gives it an adavantage if theres an environmental change

Question 7

What happens if a mutation gives an advantage?

Answer 7

If a mutation provides an advantage in an environment it makes the organism more likely to survive and breed in the conditions (or new conditons if a change in environment has taken place), causing the mutated gene/ allele to be passed on through generations until it is very common

Question 8

What is a species

Answer 8

A group of organisms that can reproduce with one another in nature and produce fertile offspring

Question 9

What causes the formation of a new species?

Answer 9

When two populations of one species become so varied in phenotype/ alleles that they can no longer breed together and produce fertile offspring

Question 10

What is evolution?

Answer 10

The gradual change in the inhertited characterisics of a population over long periods of time

Question 11

What is mutation?

Answer 11

A change in the order of the DNA bases

Question 12

How frequently do mutations happen?

Answer 12

Continuously, rarley leading to a new pheonotype

Question 13

What is selective breeding?

Answer 13

Breeding plants/ animals for particular characteristics

Question 14

What is variation?

Answer 14

Differences in the characteristics/ alleles/ phenotypes of individuals in a population

Question 15

How do new phenotype variations occur?

Answer 15

Mutations

Question 16

What is the slective breeding process?

Answer 16

1. Selecting parents with desired characteristics from a mixed population
2. Breed them together
3. Choose offspring with the desired charactersitic and breed them
4. Continue over may generations until all offspring show the desired characteristics

Question 17

For what reason can characteristics be chosen for selective breeding?

Answer 17

Usefulness or appearance

Question 18

List 2 useful characteristics commonly chosen in selective breeding

Answer 18

• Disease resistance in crops
• Animals that produce larger yeils of milk/ meat

Question 19

List 2 apperance-based characteristics commonly chosen in selective breeding

Answer 19

• Domestiated dogs with gentile nature
• Large/ unusual flowers

Question 20

What is inbreeding?

Answer 20

When some breeds are particularly prone to diease or inhertied defects

Question 21

What are the disadvantages of selective breeding?

Answer 21

• Can lead to inbreeding
• Reduces genetic variation, meaning an entire species could be suseptable to a cetain disease
• Not natural - can cause implications in nature such as calfs being born so large that the mother cannot naturally deliver (c-section)

Question 22

What are the advantages of selective breeding?

Answer 22

• Can increase useful things such as disease reistance
• Can increase crop yeilds in plants
• Can produce stronger/ fitter animals

Question 23

What is genetic engineering?

Answer 23

Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 24

What is a plasmid?

Answer 24

A small circular peiece of DNA found in bacterial cells

Question 25

What is a restriction enzyme?

Answer 25

Enzymes used to cut DNA at a specific sequence of bases (genetic sciccors)

Question 26

What enzyme is used as ‘genetic scissors’ in genetic engineering?

Answer 26

Restriction enzyme

Question 27

What enzyme is used as ‘genetic glue’ in genetic engineering?

Answer 27

Ligase enzyme

Question 28

What is ligase enzyme?

Answer 28

Enzymes used to join sections of DNA together (genetic glue)

Question 29

What is vector?

(In terms of genetic engineering)

Answer 29

A genetically modified plasmid that carries the desired gene into a bacterial cell

Question 30

What does it mean when an organism is genetically modified?

Answer 30

When it contains combined DNA from more than one organism

Question 31

How is insulin produced by genetic engineering?

Answer 31

1. Insulin gene is cut from a chromosome from donor cell using restriction enzyme. The same resitriction enzyme is then used to cut open a plasmid to ensure they will eventually fit together
2. Insulin gene is then inserted into plasmid using the ligase enzyme as ‘glue’; plasmid now a vector
3. New genetically modified plasmid (vector) is inserted into bacterium using electric shock treatment (to temporarliy make cell membrane permiable to plasmid so it can enter bacterium)
4. Finally bacterium multiplies by binary fission, each bacterium now possesses insulin so can produce its own insulin - The insulin is then separated from bacteria, purified and collected for use

Question 32

How does the electric shock treatment work?

Answer 32

Temporarily makes cell membrane permeable to plasmid so it can enter bacterium

Question 33

Why is being able to produce lots of insulin useful in medical industry?

Answer 33

To help treat diabeties

Question 34

What are herbicides?

Answer 34

Chemicals that kill/ damage weeds

Question 35

How is genetic engineering used with plants/ animals?

Answer 35

The gene/ desirable characteristic is cut out of one organism and transferred to the genetic mateiral of another organism at an early stage of their development so that they develop with the desired characteristic

Question 36

Give 4 advantages to genetic modification in agriculture

Answer 36

• GM plants can be modified to produce greater yields, increasing profit for farmers etc…
• GM plants can be modified to contain gene for poison that kills insects when they eat the plant to act as a deterrent and increase there life span perhaps
• GM plants can be modified to provide immunity to certain diseases, preventing a crop being wiped out
• GM plants can be modified to be resistant to herbicides so they can be freely applied to a crop and only kill the weeds

Question 37

Give 5 disadvantages to genetic modification in agriculture

Answer 37

• GM plants that have increased yeild could be harder to maintain/ cost more to maintain e.g. more water, herbicide, fertiliser etc…
• GM plants with poison genes would be preventing insectrs from feeding, affecting biodiversity in ecosystem and perhaps pollination by insects
• GM plants with immunity to disease would suffer from low genetic variation, implying that if another dieases were to come around that the plants were not immune to, as there is no variation, the entire crop would get wiped out
• GM plants havent been confrimed to be 100% safe, we dont know to long term affects of eating GM plants
• GM plants could lead to cross pollination to weeds, creating herbicide immune/ poision, disease immune ‘super weeds’

Question 38

What is the main ethical objection to genetic engineering?

Answer 38

The fear of human engineering - designer babies, parents could choose features, strentgh, intelligence etc..

Question 39

What is the main goal for genetic engineering in humans?

Answer 39

To cure inhertied disorders via screening embryos in things life IVF to detect the presence of the faulty genes then using gene therapy to replace the faulty genes with fully functional ones

Question 40

What is tissue culture?

Answer 40

Using small groups of cells from a part of a plant to grow identical new plants. (This is vital in preserving rare plant species)

Question 41

How does tissue culture work?

Answer 41

1. Taking cutting from plant wanted for cloning (scraping off a few cells)
2. Planting them in nutrient and hormone ritch soil (can use rooting powder/ rooting hormone powder to promote root growth)

Question 42

How does rooting powder/ rooting hormone powder work?

Answer 42

Synthetic auxins are used in hormone rooting powders to replicate natural growth conditions in plants, and encourage roots to form

Question 43

What do you have to ensure during tissue culture?

Answer 43

You must ensure the entire process is ASEPTIC/ IN STERILE CONDITIONS (carried out in the absence of harmful bacteria) other wise the new plants will rot and suffer

Question 44

What is cutting?

Answer 44

An older, but simple method of cloning - taking large stem, leaf, root cuttings from a plant and planting them in a damp atmosphere with hormone rooting powders to promote root growth until roots develop

Question 45

Why are leaves some leaves removed on cuttings before they are planted?

Answer 45

To reduce transpiration rates e.g. less leaves = less water lost (to conserve water)

Question 46

What are embryo transplants?

Answer 46

Splitting apart cells from a developing animal embryo before they become specialised, then splitting it apart into several clums and finally transplanting the identical emrbyos into host mothers who will eventually give birth to the clones

Question 47

How does adult cell cloning work?

Answer 47

1. Nucleus is removed from an unfertilised egg cell
2. The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell
3. An electric shock stimulates teh egg cell to divide to form an embryo
4. The embryo cells contain the same genetic information as the organism that supplied the adult skin cell
5. When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development

Question 48

What is the main issue with adult cell cloning?

(Happend to dolly the sheep)

Answer 48

The cells are already old and aged by the time they are used again to from an embryo for the clone; therefore the die only after a few years of the clone becoming mature, ulimately leaving the clone with a unusually short lifespan due to all its cells in its body already being old

Question 49

Give 2 reasons why hormone rooting powder is used

Answer 49

• To promote root growth
• Contains anti-microbal properties to assist in keeping the cutting treatment 100% aseptic

Question 50

Give 2 reasons why gardeners would prefer to use cuttings over seeds?

Answer 50

• Quicker than growing seeds
• Keeps the desired traits
• A seed is sexual reproduction and therefore involves the random fiusion of gametes so wont 100% be the same/ identical as the parent plants whereas cutting would produce identical to parent plant