Biology Unit 2

Question 1

What is variation?

Answer 1

Difference in organisms

Question 2

Intraspecific

Answer 2

difference between organisms of the same species

Question 3

interspecific

Answer 3

difference between organisms of different species

Question 4

Discontinuous variation

Answer 4

characteristics fall into certain groups with no overlap. determined by genetics

Question 5

Continuous variation

Answer 5

characteristics show a range. determined by genetic and environmental

Question 6

Standard deviation

Answer 6

spread of data around the mean

Question 7

why is standard deviation better than range

Answer 7

range is affected by outliers and its only the largest mine the smallest

Question 8

if SD of two different means overlap what does it imply

Answer 8

its due to chance and the difference between them is not significant.

Question 9

if SD of two different means don’t overlap what does it imply

Answer 9

its not due to chance and the difference is significant

Question 10

building block of dna

Answer 10

nucleotide

Question 11

dna structure

Answer 11

2 polynucleotides joined by hydrogen bonds between complementary bases - coils into helix

Question 12

benefits of dna as a double helix

Answer 12

more stable, beneficial in semi conservative replication, more compact

Question 13

what is a gene

Answer 13

a section of DNA that contains the coded info for making polypeptides and functional RNA. made out of introns an exons.

Question 14

how does a gene/exon code for a protein

Answer 14

made out of sequence of bases
each 3 bases code for one amino acid
therefore sequence of bases determines of triple codes which determine the amino acid sequence = primary structure, secondary into tertiary

Question 15

degenerate

Answer 15

each amino acid has more than one triplet code

Question 16

non overlapping

Answer 16

each base is read only once

Question 17

universal

Answer 17

in all organisms the same triplet codes for the same amino acid

Question 18

stop codes

Answer 18

occurs at end of sequence

Question 19

how does mutations lead to non functional enzyme

Answer 19

1. changes in sequence of bases, 
triplet codes, 
amino acids, 
primary and tertiary structure,
active site

2. substrate no longer complementary
3. no longer form enzyme- substrate complex

Question 20

what is a chromosome

Answer 20

formed during interphase, made of 2 identical chromatids joined by a centromere

Question 21

what is a homologous pair of chromosomes

Answer 21

a pair of chromosomes, 1 from mother (maternal) 1 from father (paternal), carries the same genes cos of loci but different alleles - 23 pairs

Question 22

mitosis cell produces

Answer 22

2 genetically identical daughter cels, diploid (full set of data)

Question 23

meiosis cell produces

Answer 23

4 genetically different daughter cells, haploid (half the data)

Question 24

how does meiosis produce variation

Answer 24

crossing over

independent segregation

Question 25

what is crossing over

Answer 25

occurs in prophase 1 and meiosis 1, homologous pairs of chromosomes wrap around each other and swap sections of chromatids - produces new combination of alleles.

Question 26

what is independent segregation

Answer 26

homologous pairs of chromosomes separate in meiosis 1 and its completely random. and the chromatids then separate In meiosis 2. the four daughter cells produced have different combinations of maternal and paternal. shuffling leads to GV in any potential offspring.

Question 27

difference between metaphase 1 and 2

Answer 27

in 1 = homologous pairs line up in centre of cell - 23 pairs | in 2 = single chromosomes line up in middle of cell - 23 chromosomes

Question 28

DNA mass in meiosis

Answer 28

quarters

Question 29

chromosome number in meiosis

Answer 29

halves

Question 30

genetic diversity

Answer 30

the number/ variety of different alleles of genes within a population of/or species

Question 31

benefit of high genetic diversity

Answer 31

species able to adapt with changes in the environment

Question 32

what is genetic bottleneck

Answer 32

large reduction in population size due to a natural disaster, low number of individuals = low variety of alleles so low genetic diversity

Question 33

adaptations of gills in fish

Answer 33

many gill filaments and gill lamella - large surface area thin wall permeable ventilation brings in pure water - high oxygen conc circulation brings in deoxygenated blood countercurrent flow maintains conc gradient as flow in opposite directions

Question 34

what is a xerophyte

Answer 34

a plant adapted to reduce water loss - survive in dry conditions

Question 35

what is classification

Answer 35

placing organisms into groups

Question 36

what is hierarchical classification

Answer 36

large groups divided into smaller groups with no overlap

Question 37

species

Answer 37

a group of individuals with similar characteristics that can interbreed to produce fertile offspring

Question 38

phylogenetic classification

Answer 38

based on evolutionary relationships - how closely related different species are and how recent a common ancestor they have is

Question 39

benefits of courtship behaviour

Answer 39

- identify same species - identify opposite gender - identify when individuals is ready for mating - form a pair bond

Question 40

5 ways an antibiotic can destroy a bacteria

Answer 40

1. prevent cell wall from forming, water enters by osmosis 2. increase membrane permeability 3. inhibit DNA replication 4. inhibit protein synthesis 5. inhibit respiration

Question 41

how a population of a antibiotic may become resistant to an antibiotic?

Answer 41

- variation in the population - some of the bacteria are resistant to the antibiotic - have an antibiotic resistant gene - if antibiotic is used, the ones with resistant genes survive and others will die out (selection) - the resistant ones will survive and pass on their resistant genes by vertical gene transmission and horizontal gene transmission - if this occurs for many generations, then most of the bacteria will be resistant to the antibiotic (adaptation).

Question 42

what is species diversity

Answer 42

number of diff species and number of individuals for each species