Inheritance

Question 1

DIFFERENCES BETWEEN ASEXUAL AND SEXUAL REPRODUCTION

Answer 1

1) sexual: 2 parents, asexual: 1 parent

2)sexual:meiosis, asexual:mitosis

3) sexual:fusion of gametes asexual: no fusion of gametes

4)sexual:non-identical offspring, asexual: clones/ genetically identical offspring

5)sexual:results in wide genetic variation, asexual: no mixing of genetic information

Question 2

advantages of sexual reproduction

Answer 2

-produces variation in offspring
-survival advantages due to natural selection

Question 3

define fertilisation

Answer 3

the fusion of male and female gametes

Question 4

advantages of asexual reproduction

Answer 4

-only one parent needed
-time and energy efficient as do not need to find a mate
- faster
-many identical offspring can be produced when conditions are favoruable
-successful traits passes on as off-spring are identical

Question 5

disadvantages of sexual reproduction

Answer 5

-finding a mate can be time consuming
-slower than asexual reproduction

Question 6

disadvantages asexual reproduction

Answer 6

-reduced genetic variation -survival disadvantage if environment changes
-harmful mutations in parent would be passed onto offspring

Question 7

how do malaria parasites reproduce

Answer 7

asexually in human hosts but sexually in mosquitoes

Question 8

how do fungi reproduce

Answer 8

asexually by spores but sexually to give variation

Question 9

how do plants reproduce asexually & sexually

Answer 9

asexually:
bulb division
or runners

sexually:
seeds

Question 10

define gamete

Answer 10

specialised cell formed by meiosis

Question 11

define chromosome

Answer 11

long molecule found in the nucleus of cells made from DNA

Question 12

define gene

Answer 12

part of chromosome that codes for a protein

-some characteristics controlled by a single gene, but most are controlled by genes interacting

Question 13

define allele

Answer 13

different forms of the same gene

Question 14

define dominant allele

Answer 14

allele that only needs one copy to be expressed

Question 15

define recessive allele

Answer 15

allele that needs 2 copies of the same allele for a trait

Question 16

define homozygous

Answer 16

when an individual carries 2 copies of the same allele for a trait

Question 17

define heterozygous

Answer 17

when an individual carries 2 different alleles for a trait

Question 18

define genotype

Answer 18

combination of alleles an individual has

Question 19

define phenotype

Answer 19

physical expression of the genotype the characteristic shown

Question 20

what shape is dna

Answer 20

double-helix

Question 21

what is each strand of dna, how many strands does dna have

Answer 21

dna has 2 strands

each strand is a polymer made of smaller molecules

Question 22

define gene

Answer 22

small section of DNA on a chromosomes that codes for a specific sequence of amino acids, to produce a specific protein

Question 23

define genome

Answer 23

the entire genetic material of an organism

Question 24

what is a polymer made up of

Answer 24

4 nucleotides

Question 25

what is the structure of a nucleotide

Answer 25

phosphate group attached to a sugar molecule attached to a base

Question 26

what does studying the genome allow scientists to do

Answer 26

-search for genes linked to different diseases -understand and treat inherited disorders -trace human migration patterns from the past

Question 27

what never changes in DNA

Answer 27

the phosphate group and the sugar molecule

Question 28

what are the 4 different bases

Answer 28

A, C, G, T

Question 29

the dna strands are complementary what does this mean?

Answer 29

means the same bases always pair on opposite strands AT GC

Question 30

a sequence of - bases codes for a particular amino acid

Answer 30

3

Question 31

what do the order of bases determine

Answer 31

the order in which amino acids are assembled to produce a specific protein

Question 32

what does the order of amino acids determine

Answer 32

the shape of the protein- this may determine its function

Question 33

what is the order of amino acids in a protein determined by

Answer 33

the sequence of bases in the gene for that protein

Question 34

where do the 2 stages of protein synthesis take place

Answer 34

1. takes place in nucleus 2. takes place in cytoplasm

Question 35

what is the 1st stage of protein synthesis

Answer 35

TRANSCRIPTION -base sequence of gene is copied intoa. complementary template molecule template called messenger RNA or mRNA mRNA is a single stranded molecule this mRNA passes out of nucleus into the cytoplasm

Question 36

what is the 2nd stage of protein synthesis

Answer 36

TRANSLATION in this stage, the mRNA molecule attaches to a ribosome amino acids are brought to amino acids on carrier molecules (transfer RNA or tRNA) the ribosome now reads the triplets of bases on the mRNA -and uses this to join together the correct amino acids in the correct order once protein shape is complete, it now folds into its unique shape

Question 37

what does the shape enable a protein to do

Answer 37

its job

Question 38

what does the shape enable a protein to do

Answer 38

its job

Question 39

what is a mutation

Answer 39

a change to a base

Question 40

why are more mutations harmless

Answer 40

because they do not alter the appearance or function of the protein the DNA produces

Question 41

what is cystic fibrosis

Answer 41

a disorder of cell membranes

Question 42

what allele is cystic fibrosis caused by

Answer 42

recessive

Question 43

what is polydactyly

Answer 43

extra fingers or toes

Question 44

what allele is polydactyly caused by

Answer 44

dominant

Question 45

what do non-coding parts of the dna control

Answer 45

the expression of genes by turning them on/off

Question 46

what is embryo screening

Answer 46

where embryos are tested to see if they have the alleles for inherited disorders embryos that do not have defective allels are implanted into the woman these can develop into healthy offspring

Question 47

problems with embryo screening

Answer 47

1. it is expensive 2. unethical as large number of embryos are created but small number are implanted so some are destroyed 3. find it unethical or be able to pick embryos with desirable features

Question 48

what is gene therapy

Answer 48

in furture scientists may be able to correct faulty alleles to treat inherited disorders -still experimental