WACE shit Flashcards
Approximately when did life first evolve on Earth?
approximately 3.5 billion years ago
List three structural properties of an RNA molecule.
type of nucleic acid
1–3
contains ribose sugar
phosphate group
made up of nucleotides/nitrogenous bases/contains C, G, A
and U bases
single stranded molecule
Define the term ‘genetic code’.
set of rules that determine how genetic information/nucleotide
sequences/codons in DNA/RNA is translated into amino
acids/determines amino acids in a protein
how information in DNA/RNA is converted into a protein
base triplet code that determines amino acids in a protein
Outline how the fact that all living organisms use essentially the same genetic
code provides evidence for evolution.
Organisms inherit genetic code from their ancestors.
All organisms can be traced back to a single ancestor.
role of RNA polymerase: in protein synthesis
(enzyme that) catalyses the synthesis of mRNA from DNA
or adds nucleotides to mRNA molecule
role of transcription in protein synthesis
process of making a mRNA copy of a DNA/gene sequence 1
role of anticodon in protein synthesis
(three) nucleotides in tRNA that is complementary to codon in mRNA
or (three) nucleotides in tRNA that bind to mRNA
or that determine which amino acid tRNA carries
role of ribosome in protein synthesis
reads the mRNA/site of protein synthesis/performs translation/links amino
acids (in correct order)
role of amino acid in protein synthesis
amino acids are the building blocks of protein/polypeptide
or sequence of amino acids determine type of protein
Define the term ‘mutation’
A permanent change in DNA/a gene/a chromosome. 1
List three distinctly different causes of mutation
errors in DNA replication
errors in cell division
mutagens/environmental factors
Explain the role that mutation has played in diversifying life on Earth.
mutation is source of genetic variation or of all new alleles/new genes
these are the basis of differences among organisms
mutations have accumulated over time
differences among organisms/the diversity of organisms have increased over time
without mutation all organisms would be the same (except for environmental differences)
Outline two main ways in which rodents that live in deserts lose water to the
environment.
breathing/exhaling/panting and
evaporation of moisture from lungs
excretion/urination/expelling waste/defaecation and
water is needed to excrete urea/urine or to expel faeces/waste
sweat glands/sweating and
evaporation of water from skin
Kidney mass as a percentage of body mass is often higher in rodents that live in deserts
than in related species that live in moist environments. Explain why.
desert rodents need to minimise water loss or rodents in moist
environments do not need to minimise water loss
the kidney is used to maintain salt-water balance/control the amount of
water excreted/reabsorb water
(in desert rodents) large amounts of water are reabsorbed/recovered
from urine or urine is highly concentrated
larger kidney size gives larger area for water reabsorption or the Loop
of Henle is longer in (some) desert rodents
the Loop of Henle (is the part of the kidney that) recovers the water
Define the term ‘gene pool’.
all of the genetic information/genes/alleles in a population/species
Define the term ‘allele’.
a form/version of a gene
Propose an explanation for the increase in the frequency of the AceR allele in
Population 2 during the study.
Natural selection/selective pressure of insecticide
the AceR allele gives resistance to the insecticide
individuals with AceR allele survive/reproduce/are fitter/produce more
offspring
the AceR allele is passed to offspring/inherited
more individuals in the next generation have AceR allele
process is repeated over multiple/10 generations leading to
progressive increase in frequency of the AceR allele
Distinguish between a dominant and a recessive allele.
dominant – only one copy of allele is needed for an individual to show phenotype or heterozygote will show phenotype
recessive – two copies of allele are needed for an individual to show phenotype or only recessive homozygote will show phenotype or can be masked by a dominant allele
Distinguish between autosomal and sex-linked alleles
autosomal – alleles are on autosomal chromosomes or alleles are not on sex chromosomes or two alleles are present in both males and females
sex linked – alleles are on sex chromosomes or X/Y chromosome or two alleles are present in females and only one is present in males
Outline an approach that can be used to
determine whether an unaffected individual has the SLS allele
- DNA sequencing or (comparative) genomics 1
- determine nucleotide sequence
- compare genomes/DNA sequences of affected and unaffected sheep
- take samples from affected and unaffected sheep
- extract DNA
- use PCR/restriction enzymes/gel electrophoresis
Explain what a polygenic trait is.
- controlled/influenced by the alleles at many genes/by many genes
- also influenced by the environment
- trait shows many different phenotypes in a population or trait shows continuous variation/a normal distribution in a population
Outline one advantage and one disadvantage of producing this line of sheep by artificial selection
rather than transgenesis.
ADVANTAGE
- (breeding sheep is a) natural process
- can be done on farm/does not require specialist equipment/less controversial
DISADVANTAGE
- artificial selection changes allele/gene frequencies gradually
- slower process or will take many generations to produce desired line
Define ‘homeostasis’
The process organisms use to maintain constant internal
conditions or ability to maintain stable internal conditions/state.
State the aspect of homeostasis in the frog host that is disrupted by
chytridiomycosis.
salt-water balance/water balance/salt balance/osmosis/
gas exchange
how chytridiomycosis is transmitted between frogs.
pathogen/fungi/zoosporangia release spores/zoospores (into
environment/water)
spores/zoospores are motile/swim/transported by water to new frog
by direct/skin contact between frogs
(spore/zoospores) invade skin/epidermal cells of new frog.
Distinguish between the reliability and validity of an experiment.
Reliability is the chances of getting the same/similar result (if the experiment was to be repeated)
Validity is when the experiment tests the hypothesis/what is intended to be tested.
Explain how knowledge of the reproductive behaviour of a frog species can assist with
conservation planning to minimise population decline.
- reproductive behaviour influences reproductive success
- can use information to predict/understand how it will change
- population size/population dynamics
- document courtship/mating behaviour
- can add protections to minimise disruptions to behaviour
- can manipulate behaviour/population sex ratios
- can ensure species can behave normally in captive breeding
- document nesting sites
- can protect nesting sites/add suitable/artificial nesting sites
Explain the circumstances in which it is an advantage to an animal to excrete uric acid.
dry/low water conditions
(uric acid) is not very soluble
requires very little water to excrete
compensates for high cost of production (in dry environment)
in eggs where it is not possible to remove waste
(uric acid) has low toxicity
minimises weight for flight
On the basis of the above information, how many chromosomes would be present in a
diploid cell of a mule? Explain your answer.
horse sperm/egg/gamete/haploid cell = 32 chromosomes
donkey sperm/egg/gamete/haploid cell = 31 chromosomes
egg and sperm/gametes fuse/haploid cells fuse to form
zygote/mule/offspring
32 + 31 = 63
Explain why mules cannot produce functional gametes.
meiosis is used to produce gametes
meiosis is disrupted
mules have an odd number of chromosomes/chromosomes do not
match up/chromosomes do not form pairs (in meiosis)
(therefore) chromosomes do not segregate (to different
poles/gametes) correctly
produce gametes with the wrong number of chromosomes/genes
mules do not have all of the genes/chromosomes needed (to
produce functional gametes)
mules are hybrids/sterile or mules have the genes/chromosomes of
two different species
Explain how biologists know about the evolution of the forefeet in horses over the past
50 million years.
fossils/fossil record
preserved bones (from forefeet)
bones are likely to be preserved/common in the fossil record
compare fossil evidence with forefoot in modern horse/comparative
anatomy
can age fossils using index fossils/date bones/date rock (in which the
fossil was found)
Is the evolution of horse forefeet an example of microevolution or macroevolution?
yes lol
evolution above the level of the species
major or large-scale changes
over a long period of time/millions of years
trend within a large group/taxon
accumulation of many small/microevolutionary changes
A non-albino male and a non-albino female guinea pig were crossed and produced a
litter containing some albino and some non-albino offspring. Explain in words how nonalbino guinea pigs can produce albino offspring.
albinism is recessive/coloured fur is dominant
need two recessive alleles/need to be homozygous to be albino
male and female parents were (both) heterozygotes/carried albino
allele
thus possible to get one albino allele from each parent
Both male and female albino offspring were produced in the cross described in part (a).
On this basis, explain in words why albinism cannot be a sex-linked trait in guinea pigs.
X-linkage
not possible for non-albino parents /non-albino father to produce
albino daughter/female offspring
father/males only has one X chromosome
father does not have albino allele on X chromosome (otherwise it
would be albino)
daughters/female offspring inherit one X chromosome from father
therefore not possible for any daughter/female offspring to have two
albino alleles
Y-linkage
male parent is not albino therefore no albino allele on Y chromosome
albino sons/male offspring only possible if male is albino OR albino
sons/male offspring not possible if male parent is not albino
albino daughters/female offspring are not possible because they do
not have Y chromosome
Albino guinea pigs are common in captive populations but rare in wild populations.
Explain this difference.
albino favoured in captivity/selectively breed/breed by
humans/artificial selection
(albinos) pass albino allele to offspring
albino allele increases in frequency
coloured favoured in wild or albino not favoured
by natural selection
coloured better camouflaged/tolerant of sunlight or albino poor
camouflage/sensitive to sunlight
coloured breed more or albino breed less
pass coloured allele to offspring or albinos do not pass allele
coloured allele frequency increase or albino allele frequency
decreases/kept low
Explain how biotechnology can be used to determine the father of the litter.
DNA profiling
extract DNA
Polymerase chain reaction (PCR)/amplify gene or alleles or markers
screen samples using gel electrophoresis or sequence samples
specific details of any of the methods (e.g. gel electrophoresis DNA
samples separate according to size)
compare profile of all guinea pigs
offspring will have alleles/markers from male (and female) parent
Malaria is caused by a protist. Describe the main structural features of protists.
eukaryote/eukaryotic cell
nucleus
(may have) multiple nuclei
mitochondria/membrane bound organelles
(usually) single cell
(usually) small/microscopic
cilia/flagella/pseudopodia
may have cell wall or protective outer layer
Describe how malaria is transmitted from an infected person to an uninfected person
female mosquito/Anopheles mosquito
vector
bites/takes blood from infected person
blood contains protist
protist reproduces in mosquito
transmitted when mosquito bites
transmitted in (mosquito) saliva
Outline two distinctly different methods of controlling the spread of malaria.
use of insecticides
to kill mosquitoes
or
eliminate standing water/oil on water
remove/disrupt mosquito breeding
or
modify human behaviour/avoid being outdoors at times when
mosquitoes are active/use netting/use repellent/wearing protective
clothes
avoid being bitten (stops transmission)
or
biological control of mosquito
specific details of biological control (e.g. mosquito fish)
or
anti-malaria drugs
fewer infected people/fewer pathogens in the people
Describe the distribution of malaria.
rarely occurs above or below the tropic of cancer or the tropic of
capricorn respectively
centered on the equator/occurs mainly between the tropic of cancer
and the tropic of capricorn
most countries either have malaria transmission or not
very few areas are at limited risk of malaria transmission
refers to any specific country or area where malaria transmission
does occur
states any environmental or economic factor regarding temperature
and rainfall and malaria transmission
Explain why tuberculosis is
much more widely distributed than malaria.
different types of transmission
tuberculosis is caused by bacteria
transmitted from person to person/no vector involved
(tuberculosis) transmitted by close contact/droplets/sneezing
therefore (potentially) spreads (readily) to wherever there are people
modern transport/movements of people helps spread/tuberculosis
asymptomatic
malaria is transmitted through vector/mosquitoes/transmitted
indirectly
distribution of vector influences distribution of disease or distribution
of malaria reflects distribution of (Anopheles) mosquito that transmits
it/vector
explain the process of binary fission
Chromosome/Genetic material is replicated/duplicated
Duplicated chromosome/Genetic materials moves to opposite end of
cell/segregate
Cell grows/gets large
Each copy of duplicated chromosone attaches to a different part of the
cell membrane
Cell divides into two daughter cells/cytokinesis
New cell wall is laid down
Each daughter cell has a copy of chromosome/genetic material/is
identical to the parent
RNA and DNA differences
DNA contains deoxyribose sugar
RNA contains ribose sugar 1–2
DNA contains thymine
RNA contains uracil 1–2
DNA (usually) occurs in the nucleus
RNA occurs in nucleus and cytoplasm or RNA occurs in cytoplasm 1–2
DNA contains genes
RNA translates/transfers genetic code 1–2
DNA is (usually) double-stranded
RNA is single stranded 1–2
DNA is self replicating/synthesized from DNA
RNA is synthesized from DNA
Describe the
main features of a negative feedback mechanism.
Change in internal environment
Brings about a response/stimulus triggers a response
Receptor that senses change
Response counteracts the change/feedback alters the stimulus
Processing centre/control centre/modulator processes the
signal
Effector carries out the response/a response is carried out
endothermic definition
Endothermic is the term used to describe an animal that regulates
it body temperature independently of the external environment
ectothermic definition
Ectothermic is the term used to describe an animal whose body
temperature fluctuates with the external environment
Does a large body size will help a mammal to retain body heat in a cold environment?
A large body has a low surface area to volume ratio and so will lose
less body heat to the environment
Name the process used by a mammal to generate body heat
Metabolism/metabolic rate/respiration
Explain how blubber helps a marine mammal to retain body heat in cold water
Blubber insulates/prevents heat transfer (from mammal to
water)/Blubber is a poor conductor of heat
Blubber surrounds the body of the mammal
Separates warm core of body from the cold water/external
environment
Heat is retained in the core of the body
Many plants and animals use evaporative cooling in thermoregulation. Explain the main
principles of evaporative cooling.
Water evaporates/Changes from liquid to gas
This requires energy
This energy is taken from the plant or animal
Results in cooling
Water vapour is released from the plant or animal
State how infectious diseases differ from other types of diseases. (
Caused by a pathogen/organism 1
Can be transmitted from one host to another/contagious
Explain the main principles of herd immunity.
Large proportion of the host population become immune
Immunity can be gained naturally/by recovering from disease or
immunity can be gained artificially/by a vaccine
Limits the spread of the disease/too few susceptible individuals to
sustain the spread
Pathogens/infected hosts/infected people mainly come into contact
with immune hosts/immune people
Ultimately reduces the risk for susceptible individuals (because
disease is relatively rare)
Higher the proportion of the population that is immune, the greater the
protection
Protects (vulnerable) individuals who cannot be vaccinated
The exact proportion depends on virulence and infectivity of a
particular disease
Global climate change is
predicted to increase the risk of malaria transmission at higher altitudes in tropical
regions. Explain why
(Malaria is) Transferred by mosquito/Mosquito vector/Anopheles
Mosquito thrives in a warm environment/Is restricted to warm
environment or/Is rare in cooler environments/at higher altitudes
(Global climate change will) increase temperature at higher altitudes
Mosquito will spread to higher altitudes or will increase in abundance
at higher altitudes or will be more active at higher altitudes
Mosquito will take the disease with it when it spreads or people are
more likely to be bitten if mosquitoes are more abundant/more active
(Higher temperature) Will speed up the life-cycle of the
pathogen/Plasmodium/protozoan
This will increase the abundance of the pathogen
Greater abundance of pathogen, means the risk of transmission is
higher
Explain how a disease-causing strain of bacteria can evolve resistance to an
antibiotic used to treat the associated disease.
Affected people were treated with the antibiotics
Antibiotics killed bacteria in most individuals/cured most individuals
This halted the spread/killed off of antibiotic sensitive strains of the
bacterium
A bacterium acquired resistance to the antibiotic
Through mutation or through the acquisition of a plasmid with a
resistance gene
These resistant bacteria were unaffected by the antibiotic
The antibiotic resistant bacteria continued to be transmitted/continued
to reproduce
Therefore the antibiotic resistance bacteria are becoming more
common
Natural selection favoured the antibiotic resistance strains or the
antibiotic sensitive strains were selected against
Pathogens evolve rapidly in changing environment (antibiotic
represents a change environment).
List the main steps involved in producing a DNA profile for an organism.
Extract/Isolate/Obtain DNA/from organism 1
Use PCR/cloning to produce a large amount of DNA/of a particular DNA
sequence
1
Sequence DNA/use restriction enzymes to produce fragment
profile/Amplify DNA region with repeat units/VNTR/STRs 1
Use electrophoresis to visualize/separate out different pieces of DNA 1
T
Explain how DNA profiling could be
used to determine whether these people had contracted the virus through the dental
practice.
Create DNA profile of the virus in these patients.
Create/obtain DNA profile of hepatitis virus from other sources
Compare the DNA profiles
If patients contain same/related strains of virus, then it likely came from
the dental practice.
Use phylogenetic tree to show the relationships among the viruses
from the different sources
role that Restriction enzyme plays in gene cloning.
cuts (target) gene from donor organism or cuts plasmid DNA so gene can
be inserted
role that plays ligase in gene cloning.
binds (target) gene to plasmid DNA
role that plays Plasmid in gene cloning.
makes large amounts of (target) gene
role that plays vector in gene cloning.
introduces (target) gene to recipient organism
Explain an advantage of using DNA recombinant technology, rather than artificial
selection, to produce a herbicide-resistant strain of canola.
hance of finding a gene with (broad/strong/desirable)
herbicide resistance
1–2
Relatively quick
Can produce a strain within one or few generations or artificial
selection can take many generations to fix herbicide resistance in a
trait
1–2
Only manipulate herbicide resistance
Allows retention of other desirable characteristics in the strain or
artificial selection for one trait can inadvertently lead to changes in
other traits
Explain a possible adverse environmental effect that could result from farming
herbicide-resistant canola.
Any one set of answers, one mark per point.
Will not be able to use herbicides to kill the canola plant.
These plants could spread and become a nuisance. 1–2
Potential for the herbicide resistance gene to spread to other
species.
This could create a super weed/a nuisance plant that is resistant to
herbicide
1–2
Relatively new/Untried
Consequences are not fully understood 1–2
Over use of herbicide/increased use
Leading to evolution of herbicide-resistant weeds/death of
non-target species