TOPIC B6 INHERITANCE, VARIATION AND EVOLUTION

Question 1

what is DNA

Answer 1

-coded infomation put together to make an organism work

Question 2

what does DNA determine
and where is it found

Answer 2

what inhertied characteristics you have
-found in the nucleus of animal and plant cells, in long strutctrues called chrosomes

Question 3

what is DNA

Answer 3

-a polymer and is made up of 2strands coiled together in the shape of a double helix

Question 4

what does a gene code for

Answer 4

a specific protein
-codes for a particular sequence of amino acids that are put together to make specific proteins
-only 20 amino acids are used, but they make up thousands of proteins

Question 5

what’s a genome

Answer 5

an organism everyone has
-(entire set of genetic material)

Question 6

state the 2ways reproduction happens

Answer 6

-sexual
-asexual

Question 7

what is sexual reproduction

Answer 7

-where genetic material from 2organisms a mother and father combined to produce offspring

Question 8

what happens in sexual repoduction

Answer 8

-mother and father produce gametes by meosis
-e.g egg and sperm cells
-each gamete contains 23chromosomes
-the egg and sperm cell fuse together (fertilisation) to form a cell with the full number of chromosomes

Question 9

define sexual repoduction

Answer 9

involves the fusion of male and female gametes, because there are 2parents, the offspring contain a mizture of their parents genes

Question 10

state why offspring inherits features from both parents

Answer 10

-as it inherits features from both parents and recieves a mixture of chromosomes from mum and dad

Question 11

state the difference between sexual reproduction and asexual

Answer 11

-sexual produces genetically different cells whereas asexual produces genetically identical ones
-asexual involves the use of one parent
-sexual is by meiosis but asexual is mitosis

Question 12

asexual reproduction characteristics

Answer 12

-1parent so offsprings genetically identical to the parent
-happens by mitosis
-bacteria, plants and animals reproduce asexually

Question 13

define asexual reproduction

Answer 13

-theres only 1parent and no fusion of gametes, no mixing of chromosomes and no genetic variation between parent and offspring.
-offspring are genetically identical to the parent and they’re clones

Question 14

what are gametes produced by

Answer 14

meiosis
-they only have 1copy of each chromosomes so when gamete fusion takes place, you get the right amount of chromosomes again

Question 14

explain the process of meosis

Answer 14

half the normal number of chromosomes
-before the cell divides, it duplictes its genetic infomation and forms 2 armed chromosomes
-after replication the chromosomes arrange themselves into pairs
-in 1st line division the chromosome pairs line up in the centre
-pairs are then pulled apart so each cell has a copy of each chromosome

Question 15

what happens in the 2nd division

Answer 15

chromosomes line up again in the centre of the cell
-the arms of chromosomes are pulled apart

Question 16

state what happens to the cell produced by gamete fusion

Answer 16

-they replicate itself
-after theyve fused the new cell divides by mitosis to make a copy of itself
-mitosis repeats many times to produce lots of new cells in an embryo
-as embryo develops they then differentiate into new types of a specialised cell, making up a whole organism

Question 17

state what chromosome males have

Answer 17

XY
- Y causes male characteristics

Question 18

state what chromosome females have

Answer 18

XX
the XX combination allows female characteristics to develop

Question 19

what diagram do you draw to show the probability of having a boy or girl

Answer 19

-a Punnett square
(genetic diagram)

Question 20

what are alleles

Answer 20

-all genes that exist in different versions
-represented by letters

Question 21

what has to happen for an organism to be homozygous

Answer 21

if an organism has 2 alleles for particular genes that are the same

Question 22

what has to happen for an organism to be heterozygous

Answer 22

if 2alleles are different
-only 1 determines what characteristic is present
-the characterisitic shown is the dominant allele (use captial leter)
-other is recessive

Question 23

why do organisms display recessive characteristics

Answer 23

-both alleles are recessive
e.g cc

Question 24

why do organisms display dominant characteristics

Answer 24

as the dominant allele overrules the recessive one could be CC OR Cc

Question 25

what are genotypes and phenotypes

Answer 25

-combination of alleles
-characteristic you have e.g brown eyes

Question 26

genetic dirarams

Question 27

what is cystic fibrosis

Answer 27

-a genetic disorder of the cell membrane
-it results in the body producing thick sticky mucus in the air passages and in the pancreas
-caused by a recessive allele

Question 28

state a genetic disorder caused by a dominant allele

Answer 28

-polydactyly
where a babys born with extra fingers or toes
-can be inherited if 1parent carries the defective allele

Question 29

state arguments against embryonic screening

Answer 29

-screenings expensive
-may come a point where everyone wants to screen their embryos so that they can pick the most desireable one
E.G WANT ONE WITH BLUE EYES OR BLOND HAIR

Question 30

stage arguments for embryonic screening

Answer 30

-helps stop people suffering
-treating disorders costs the government a lot of money
-laws to stop it going too far

Question 31

what is variation

Answer 31

differneces that exist between individuals

Question 32

what are mutation

Answer 32

-changes to the genome
-its a rare change in an organisms DNA that can be inherited
-means the genes altered
-

Question 33

state charles darwins theory

Answer 33

-only the fittest survive
-organisms with most suitable characteristics for environment are successful competitors and would be more likely to survive
-then reproduce and pass on genes for characteristics successful to their offspring

Question 33

what is the theory of evolution

Answer 33

-that all of todays species have evolved from simple life forms that firdt started to develop over 3billion years ago

Question 34

state 3 reasons why species become extinct

Answer 34

1. environment changes too quickly
2. a new predator kills them all
3. a new disease kills them all

Question 35

what is selective breeding

Answer 35

when humans artifically select plants or animals that are going to breed so that they remain in populations

Question 36

examples of organisms that are selectively bred

Answer 36

-animals that produce more meat or milk
-crops with disease resistance
-decorative plants with big or unsual flowers

Question 37

state the basic processes involved in selective breeding

Answer 37

-selecting 1 with characteristics your after
-breed them with each other
-best of offpsring + breed together
-continue process over several generations and the desirable trait gets stronger

Question 38

main problem with selective breeding

Answer 38

-it reduces the gene pool
(the number of different alleles)
-inbreeding causes health problems

Question 39

what is genetic engineering

Answer 39

-to transfer a gene responsible for a desirable characteristic from 1 organisms genome into another organism

Question 40

pros of gm crops

Answer 40

-increases the yield
-already being grown in some places without any problems

Question 41

cons of gm crops

Answer 41

-affects number of wild flowers
-not convinced there safe
-transplanted genes may get out into natural environment

Question 42

state how fossil fuels are formed

Answer 42

1. gradual replacement by minerals
2. casts and impressions
3. preservation, places where no decay happens

Question 43

state the 3 domain system

Answer 43

• archaea
• bacteria
• eukaryota