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 does a gene code for

Answer 3

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 4

what’s a genome

Answer 4

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

Question 5

state the 2ways reproduction happens

Answer 5

-sexual
-asexual

Question 6

what is sexual reproduction

Answer 6

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

Question 7

what happens in sexual repoduction

Answer 7

-involves the joining (fusion) of male and female gametes:
-sperm and egg cells in animals
-pollen and egg cells in flowering plants.

Question 8

Why does sexual reproduction use meosis

Answer 8

as it is the mixing of genetic infomation, leading to variety in offspring

Question 9

state the difference between sexual reproduction and asexual

Answer 9

-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 10

asexual reproduction characteristics

Answer 10

-1parent so offsprings genetically identical to the parent
-no fusion of gametes
-happens by mitosis
-bacteria, plants and animals reproduce asexually

Question 11

define asexual reproduction

Answer 11

-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 12

what are gametes produced by

Answer 12

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

Question 13

explain the 1st process of meosis

Answer 13

Chromosomes duplicate – DNA replicates, b4 cell divides

1st division- chromosome pairs line up along the centre of the cell
-they are then pulled apart so each cell has 1copy of the chromosome

Question 14

what happens in the 2nd division

Answer 14

chromosomes line up again in the centre of the cell
-the arms of chromosomes are pulled apart
they then get 4 gametes with only a single set of chromsomes in it

Question 15

state what happens to the cell produced by gamete fusion

Answer 15

-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 16

state what chromosome males have

Answer 16

XY
- Y causes male characteristics

Question 17

state what chromosome females have

Answer 17

XX
the XX combination allows female characteristics to develop

Question 18

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

Answer 18

-a Punnett square
(genetic diagram)

Question 19

gamete definition

Answer 19

sex cells
e.g plants- pollen, nucleus
e.g animals- sperm

Question 20

what are alleles

Answer 20

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

Question 21

Heterozygous

Answer 21

if 2 alleles of a gene are different

Question 21

chromosomes

Answer 21

carry genetic infomation in the form of genes
-located in nucleus of cells

Question 22

dominant

Answer 22

always expressed even if only one copys present

Question 23

recessive

Answer 23

only expressed if 2 copies are present

Question 24

Homozygous

Answer 24

if 2 alleles of gene are the same

Question 25

what has to happen for an organism to be homozygous

Answer 25

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

Question 26

what has to happen for an organism to be heterozygous

Answer 26

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 27

why do organisms display recessive characteristics

Answer 27

-both alleles are recessive e.g cc

Question 28

why do organisms display dominant characteristics

Answer 28

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

Question 29

what are genotypes and phenotypes

Answer 29

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

Question 30

genetic dirarams

Question 31

what is cystic fibrosis

Answer 31

-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 32

state a genetic disorder caused by a dominant allele

Answer 32

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

Question 33

state arguments against embryonic screening

Answer 33

-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 34

stage arguments for embryonic screening

Answer 34

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

Question 35

what is variation

Answer 35

differneces that exist between individuals

Question 36

what are mutation

Answer 36

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

Question 37

state charles darwins theory

Answer 37

-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 38

what is the theory of evolution

Answer 38

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

Question 39

state 3 reasons why species become extinct

Answer 39

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

Question 40

what is selective breeding

Answer 40

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

Question 41

examples of organisms that are selectively bred

Answer 41

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

Question 42

state the basic processes involved in selective breeding

Answer 42

-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 43

main problem with selective breeding

Answer 43

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

Question 44

what is genetic engineering

Answer 44

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

Question 45

pros of gm crops

Answer 45

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

Question 46

cons of gm crops

Answer 46

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

Question 47

state how fossil fuels are formed

Answer 47

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

Question 48

state the 3 domain system

Answer 48

- archaea - bacteria - eukaryota

Question 49

Gentoype

Answer 49

combination of alleles that control the chracteristics

Question 50

phenotype

Answer 50

observable characteristics of an organism