Topic 6 Evolution and Variation

Question 1

what is variation?

Answer 1

all the differences in the characteristics of individuals of a population

Question 2

whats the first cause of variation

Answer 2

allelles the individuals have inherited ,which are genetic variation

Question 3

some variation is caused by what?

Answer 3

the environment

Question 4

what are examples of variation being caused by the environment?

Answer 4

ph of soil changing the colour of flowers or language in humans

Question 5

what are the 3 main causes of variation?

Answer 5

alleles , environment , genes

Question 6

whats an example of the 3rd type of variation?

Answer 6

Some people having alleles which will make them grow taller but theyll require more calcium in their diet for bones to fully develop so their height will b a combo of genetics and environment

Question 7

what are mutations

Answer 7

random changes to dna

Question 8

when do mutations take place and what do they have no effect on?

Answer 8

all the time,,

the phenotype

Question 9

VERY rarely, mutation can lead to a new what?

Answer 9

Phenotype, this can be beneficial if the environment changes

Question 10

when do scientists believe life first developed on earth?

Answer 10

more than 3 billion years ago

Question 11

all species of living things have evolved from what?

Answer 11

simple life forms (single cells)

Question 12

what is the process called when species evolve from simple life forms?

Answer 12

evolution by natural selection

Question 13

what is natural selection (rabbits example)

Answer 13

-every rabbit will have a different combo of alleles
-some may have alleles for thicker fur
-if environment gets colder, rabbits with alleles for thicker fur are more likely to survive, reproduce and pass allele onto children
-over generations the allele for thicker fut will become more common among population of rabbits

Question 14

what is evolution definition

Answer 14

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

Question 15

how can two rabbits become different species?

Answer 15

if they become so different in phenotype they can no longer produce fertile offspring

Question 16

what are the 4 types of selective breeding using examples

Answer 16

-dogs being bred to have a more gentle nature
-food crops being bred to resist disease
-cows being bred to produce more milk/meat
-plants being bred to produce large/unusual flowers

Question 17

how is selective breeding carried out (if you wanted to breed large cows for meat)

Answer 17

take a mixed population of cows & select the largest male and female , breed them together, select the largest male and female offspring and breed them together ,, continue this over many generations until all the offspring are large

Question 18

whats a big biological problem with selective breeding?

Answer 18

if you breed closely related animals then you can get inbreeding,, this can cause some breeds to be prone to disease or inherited defects (eg dog breeds inheriting disorders like joint problems, heart disease or epilepsy)

Question 19

what happens in genetic engineering?

Answer 19

genes from one organism are cut out and transferred to cells of a different organism (genome of second organism is modified and now includes gene from first organsism)

Question 20

example of genetic engineering for diabetic people:

Answer 20

bacteria has been genetically modified to contain human insulin, these now produce human insulin gene which can be purified and used for type 1 diabetes

Question 21

why do we love GM crops? x

Answer 21

they produce a larger yield & we can make them resistant to disease or insect attack or produce bigger/better fruits

Question 22

why do farmers love GM crops

Answer 22

some GM crops are resistant to herbacides so farmer can spray their fields to kill weeds without harming the GM crops

Question 23

what is gene therapy

Answer 23

genetic modification being explored as a way to treat inherited disorders in humans

Question 24

why is gene therapy #scary?

Answer 24

the long term effects are unknown, eg if we modify a gene we don’t know the potential effects on other genes

Question 25

what are the main steps in genetic engineering?

Answer 25

1- identify the gene we want to transfer 2-use enzymes to isolate the gene 3-transfer the gene into a small circle of DNA called a plasmid (we can use virus instead of plasmid) 4-the desired genes transferred into cells of target organism

Question 26

why are plasmids v useful?

Answer 26

they originally come from DNA so are v good at transferring DNA from one organism to another

Question 27

in genetic engineering, why do we always transfer the gene at an early stage in the organisms development?

Answer 27

to ensure that all cells receive the transferred cells so organism develops w the characteristic we want

Question 28

whats the advantage with cloning plants?

Answer 28

as the clone is genetically identical tot he og, we know exactly what the clones characteristics will be (eg the colour of flowers)

Question 29

how to clone a plant using cuttings?

Answer 29

a small piece of the plant is removed and the end is dipped in rooting powder containing plant hormones and encourages the plant to develop roots

Question 30

when may cutting method not work the greatest

Answer 30

if we want 100s of clones of a plant

Question 31

what happens in tissue culture?

Answer 31

we take a plant that we want to clone and divide the plant into hundreds of tiny pieces each containing a small n.o of cells, these groups of cells are incubated with plant hormones ,, these stimulate the plants to grow and develop into fully grown clones

Question 32

what condition must we use for tissue culture and why

Answer 32

sterile,, we do not want to introduce any microorganisms such as bacteria or fungi

Question 33

where is tissue culture extremely useful?

Answer 33

commercial plant nurseries where 1000s of genetically identical plants need to be grown cheaply and quickly

Question 34

what is tissue culture used for other than simply cloning

Answer 34

preserving rare species of plants

Question 35

what are the stages of cloning by embryo transplants

Answer 35

start with sperm and egg cell from mammal w/ characteristics we desire fertilisation produces fertilised egg allow fertilised egg to develop into an early stage embryo (cells must NOT have started to specialise) use glass rod to split embryo into two transplant 2 embryos into host mammal which will grow and develop into 2 identical offspring

Question 36

what is the main issue with embryo transplants