genetics and variation

Question 1

function of DNA vs function of RNA

Answer 1

DNA- holds genetic information
RNA- transfers genetic information from DNA to ribosomes

Question 2

strucure of DNA nucleotide

Answer 2

deoxyribose (5C) sugar, phosphate group, nitrogenous base (A&T, C&G)

Question 3

structure of RNA nucleotide

Answer 3

ribose sugar, phosphate group (adenine binds with uracil instead of thymine)

Question 4

gene definition

Answer 4

section of DNA which codes for an amino acid sequence

Question 5

codon definition

Answer 5

triplet of bases which codes for for a single amino acid

Question 6

features of the genetic code

Answer 6

non-overlapping
degenerate
contains exons and introns

Question 7

allele definition

Answer 7

alternative form of the same gene

Question 8

homologus pairs definition

Answer 8

two chromosomes that carry the same genes

Question 9

mRNA structure

Answer 9

single-stranded
complementary to the base sequence it was transcripted from
contains a ribose sugar
contains AUCGT bases

Question 10

tRNA structure

Answer 10

clover leaf shape
specific amino acid attached
contains anticodons

Question 11

describe transcription

Answer 11

DNA helicase unwinds DNA and breaks H bonds between complementary base pairs
one strand acts as a template
free RNA nucleotides align by complementary base pairs
RNA polymerase forms phosphodiester bonds between adjacent nucleotides
pre-mRNA is spliced to form mRNA
mRNA leaves nucleus via nuclear pore

Question 12

describe translation

Answer 12

mRNA attaches to a ribosome
tRNA attaches to mRNA via complementary base pairing
tRNA brings a specific amino acid with it
adjacent amino acids form a peptide bond via a condensation reaction

Question 13

polyplodily meaning

Answer 13

changes that occur in the whole set of chromosomes so an individual has more than two of the same set of chromosomes

Question 14

non-disjunction

Answer 14

chromosomes fail to separate properly

Question 15

how is genetic variation ensured via meiosis

Answer 15

independent assortment of chromosomes- chromosomes line up randomly during meiosis one
crossing over of chromatids- creates a different combination of alleles on the gene

Question 16

meiosis one

Answer 16

homologus pairs align at centre and cell divides (same as mitosis)
crossing over occurs here where chiasmata form and equal lengths of chromosomes are exchanged

Question 17

meiosis two

Answer 17

sister chromatids are separated randomly into two cells
forming two haploid daughter cells

Question 18

population definition

Answer 18

a group of individuals of the same species living within a particular area

Question 19

genetic diversity meaning

Answer 19

total number f different alleles within a population

Question 20

niche

Answer 20

a species specific role within its environment

Question 21

natural selection

Answer 21

there are a variety of pheonotypes
environmental change occurs
individuals better adapted to the selection pressure are more likely to survive long enough to reproduce and pass on their advantageous alleles to the next generation
frequency of allele increases over time

Question 22

directional selection

Answer 22

favours one extreme

Question 23

stabilising selection

Answer 23

favours the mean

Question 24

disruptive selection

Answer 24

favours both extremes

Question 25

anatomical adaptations

Answer 25

physical adaptations

Question 26

behaviour adaptations

Answer 26

e.g mating calls

Question 27

physiological adaptations

Answer 27

processes inside an organisms body

Question 28

classification list

Answer 28

Kingdom Phylum Class Order Family Genus Species

Question 29

what do courtship behaviours do

Answer 29

recognise members of their own species synchronise mating form a pair bond become able to breed

Question 30

index of diversity calculation

Answer 30

D= N(N-1)/ sum of n(n-1) where N is total number of organisms and n is total number of organisms of each species

Question 31

ecosystem diversity meaning

Answer 31

variety of different habitats

Question 32

species diversity

Answer 32

number of different species and individuals in a community

Question 33

how does agriculture reduce biodiveristy

Answer 33

humans farm for specific characteristics so the gene pool is reduced

Question 34

methods of increasing biodiversity in farming

Answer 34

hedgerows intercropping (growing multiple crops in one area) reducing herbicide and pesticide use preserving wetlands

Question 35

how to compare genetic diversity

Answer 35

comparing DNA, RNA or mRNA base sequence or amino acid sequence comparing observable characteristics

Question 36

limitations of comparing genetic diversity via observation

Answer 36

same characteristics can be coded for by different genes/ DNA base sequence same characteristics can arise seperately could be influence from environment

Question 37

interspecific variation

Answer 37

variation between species

Question 38

intraspecific variation

Answer 38

variation within species

Question 39

disadvantages of using DNA/ RNA etc. base sequence to measure genetic diversity

Answer 39

sample may not be representative