Bio p4 questions Flashcards
Sickle cell anaemia
why (haemoglobin) or cause (mutation)
Sickle cell anaemia is a disease that reduces the delivery of oxygen to tissues. Explain why -:
- Haemoglobin becomes ABNORMAL
- Abnormal haemoglobin carries less oxygen than normal haemoglobin = transport of oxygen is less
- rbc become sickle shaped
- these sickle cells CLOT in blood and REDUCE FLOW of healthy blood
Describe the cause of sickle cell anaemia
- mutation
- change in base sequence of DNA
- in allele for haemoglobin
- (people) inherit the ALLELE for mutated haemoglobin
- (why they get it?) being homozygous recessive
- so, produce abnormal haemoglobin
- rbc are sickle shaped
Some captive breeding programmes involve a very small number of animals. Outline the disadvantages of such programmes.
- that forces people to inbreed animals, so that reduces genetic variation.
- = unable to adapt to changes in environment; reducing fitness
- by natural selection they are unable to survive and reproduce
- higher competition between organisms for food, water = local extinction
Describe what happens to carbohydrates in the human body between ingestion and assimilation in the liver. [8]
- Ingestion occurs in mouth where mechanical digestion happens by teeth that grind food.
- Chemical digestion occurs as salivary glands secrete salivary amylase, so large insoluble molecules are broken down into small soluble molecules.
- amylase breaks down starch into maltose.
- MALTASE breaks down MALTOSE into GLUCOSE on epithelium lining of small intestine.
- In small intestine, villi increase surface area for absorption by diffusion
- assimilation occurs in liver, glucose converted to glycogen and stored.
Similarities and differences between marasmus and kwashiorkor. [4]
S: both caused by protein energy deficiency.
both affect children primarily
poor growth
both types of malnutrition
D: marasmus is protein and carbohydrate deficiency, but kwashiorkor is only protein (pot belly)
Describe function of arterioles in the skin. [3]
- control blood flow towards surface of skin
- help in homeostasis to maintain opt. body temp by vasoconstriction / vasodilation
- have contraction and relaxation
- deliver blood from arteries to shunt vessels
Describe the function of lymph nodes in the lymphatic system. [2]
- contain lymphocytes which produce antibodies
- help gain active immunity against pathogens
- filter lymph fluid
explain how fish stocks can be conserved by restocking. [3]
- captive breeding programmes
- release into wild
- protected areas
- limited fishing (so that wild stocks can recover) by placing fines
Features of arthropods. [2]
- exoskeleton
- segmented limbs, body
- pairs of limbs / legs
Explain the term adaptive feature [3]
- inherited feature / controlled by genes;
- increase fitness / chances of survival and
- chance of reproducing (to leave offspring)
e.g. camouflage / scares predators / lure for prey
Explain why viral diseases cannot be treated with antibiotics. [2]
viruses have no antibiotic targets ; are not living / cannot be killed / not cells;
no cell membrane ;no cell wall ; no protein synthesis, do not respire
How are flowers adapted for wind-pollination? [3]
anthers / stamens / filaments / stigma, hang outside (the flower);
large anthers /produce large quantities of pollen, easily release pollen ;
stigma has feathery surface / large surface area to catch pollen
Stem cells function. [2]
divide by mitosis to produce daughter cells that can become specialised to replace cells and for repair of any damage to tissues
Define assimilation. [2]
movement of digested food molecules into the cells of the body where they are used,
becoming part of the cells
Adrenaline is often secreted during sporting competitions. How does it affects swimmer’s performance? [3]
- heart rate increases
- breathing rate increases
- faster reaction time
- higher blood glucose
- more respiration for more energy for muscle contraction.
When eye is focusing on what’s close what happens to ciliatory muscles and suspensory ligaments? 2
Outline how humans are able to see colour. [3]
Ciliatory muscles contract
Suspensory ligaments relax
- cones respond to different wavelengths
- convert light into electrical impulses
- send them via optic nerve
- brain interprets impulses in terms of colour
Except nervous system, outline one other way in which these organs are coordinated. [2]
hormones
secreted into blood
stimulate target cells / organs
explain why the control of concentration of glucose in the blood is an example of negative feedback. [3]
- homeostasis
- glucose concentration is kept near constant
- any change in concentration detected = acts as a stimulus ;
high glucose concentration: glucose → glycogen
low glucose concentration: glycogen → glucose; - returns concentration to normal by releasing insulin/glucagon hormone
Name the vein that transports blood away from the small intestine. [1]
hepatic portal vein
Some people develop gallstones, made of cholesterol, that accumulate in the gall bladder and the bile duct. Gallstones block the flow of bile. Explain how gallstones can affect digestion of fat. [3]
emulsification
slower emulsification of fat for increased surface area of fat for lipase
State features of arachnids. [2]
- 4 pairs of legs
- fused head and thorax
Explain the term balanced diet. [3]
provides, sufficient energy, molecules / materials for metabolism, nutrients
in correct quantities
Describe what happens to seal the wound in the skin and repair the skin tissue. [5]
platelets stimulate clotting
thrombin (enzyme) converts soluble fibrinogen to insoluble fibrin
forming a mesh to prevent blood loss, forms scab
phagocytes engulf pathogens
cells divide by mitosis to make identical cells
tissues form to make epidermis / capillary / new skin
Explain how auxins control the growth response of the seedlings. [4] positive phototropism
- auxins made in shoot tip
- spread down the stem
- auxins collect away from light
- greater cell elongation on the dark side
Describe how the nervous system coordinates the response of the skin to cold weather. [4]
Explain how negative feedback is involved in the control of body temperature. [3]
- change in temperature is stimulus
- temperature receptors in skin
- send an (electric) impulse
- which travels through sensory neurone
- to brain
- relay neurone
- motor neurone
- to effector (arteriole / erector, muscle)
homeostasis
change in temperature is detected
to keep temperature constant
opposite is action by the body to return to normal temperature
Define and describe the process of deamination. [3]
removal of the nitrogen-containing part of amino acids to form urea
happens in liver
- part of excess amino acids converted to urea
- part of amino acid converted to ammonia ;
- ammonia is harmful so converted to urea ;
- rest of amino acid molecule releases energy / converted to glucose
- (some amino acids) used to make proteins
Explain how an increase in glucose concentration is controlled in the body. [3]
Explain how a decrease in water potential of the blood may damage red blood cells. [3]
homeostasis / negative feedback
- pancreas detect an increase in glucose concentration
- pancreas secretes insulin
- transported in blood / plasma
- liver convert glucose to glycogen using enzymes
- water diffuses out of red blood cells
- through partially permeable membrane
- by osmosis
- down water potential gradient
- red blood cells shrink / decrease in volume
How does HIV affect immune system? [4]
- HIV affects lymphocytes and t-helper cells
- fewer antibodies produced; phagocytes less effective
- infected cells are not killed
- increased susceptibility to opportunistic diseases
- can lead to AIDS
HIV changes its protein coat = avoids being recognised.
Describe negative consequences of letting untreated sewage flow into lake ecosystems. [6]
- female contraceptive hormones cause feminisation and reduced sperm count in aquatic animals
- eutrophication
nutrients in hormones cause algae to grow - plants die, cannot photosynthesis
- bacteria aerobically decomposes organic matter
- pH of the lake decreases
- animals die due to lack of oxygen
- food chain disrupted
- more mosquitos/flies; more water-borne disease
Vaccination [4]
- harmless form of pathogen is injected
- antigens trigger an immune response by lymphocytes which produce antibodies
= active immunity acquired - memory cells produced that give long-term immunity
Effect of cholera on digestive system. [5]
(Disease caused by a bacterium)
- produces toxin
- which causes secretion of chloride ions in the small intestine
- loss of water into the gut by osmosis
- diarrhoea
- dehydration
- watery faeces, loss of salts
why are bacteria useful in biotechnology and genetic engineering? 5
- rapid reproduction rate and
- ability to make complex molecules
- lack of ethical concerns over their manipulation and growth
- genetic code shared with all other organisms
- presence of plasmids
Enzymes in the fungus are used to make penicillin.
Explain why there is a water jacket around the fermenter and why acids or alkalis are
added to the fermenter. [6]
water jacket
- maintain optimum temperature
- to prevent enzymes denaturing, shape of active site changes
- (because as) fungus respires, it releases heat
- so temperature in the fermenter increases
- which would kill fungus ;
- therefore no product / penicillin
addition of acids or alkalis
- maintains pH
- enzymes need optimum pH
- to give maximum yield
- (otherwise) enzyme activity / rate of reaction slows
Explain why there are no more than four trophic levels in the food web shown. [3]
- Energy is lost between and within trophic levels
- only 10% energy is transferred per trophic level
- not enough energy in fourth trophic level to support another level
Describe disadvantages of intensive farming, such as salmon farming, for producing human food. [3]
- feeding is expensive
- waste feed causes eutrophication of water supplies
- diseases spread easily in captivity
- more energy efficient to feed humans on crops / animals that are used to make the (fish) food
The person leaves the room and runs very fast for 200 m. When the person stops running, his breathing rate and his heart rate remain high for several minutes.
Explain why the person’s breathing rate and heart rate remain high. [4]
- oxygen debt needs to be repaid and this takes time as more oxygen is needed than usual
- lactic acid produced as a result of anaerobic respiration, builds up in muscles
- lactic acid needs to be broken down (requires oxygen)
lactic acid, moves / diffuses from muscle) into blood ;
lactic acid transported to the liver
(in the liver) lactic acid is, broken down / oxidised / respired
The run results in changes in the skin involving the blood vessels and the sweat glands.
Describe what happens to the blood vessels and sweat glands during the run.
Explain why these changes happen. [5]
- when body temperature increases, vasodilation of arterioles occurs
- this will increase in supply of blood to skin capillaries, causing loss of heat by radiation to atmosphere
Body temp will be lowered - increase in blood flow to sweat glands
- increased production of sweat
- loss of heat by evaporation
Explain what is meant by the term involuntary action. [2]
automatic action
stimulus always leads to the same response
Describe how impulses transmitted across synapse. [3]
- impulse (at pre-synaptic neurone) triggers the release of neurotransmitters into the gap (synaptic cleft)
- diffuse across the gap
- binds to receptors (on posts-synaptic membrane)
- which allows the passage of the impulse
Explain the difference between self-pollination and cross-pollination. [2]
Discuss the long-term effects of self-pollination on the evolution of these plant species. [4]
transfer of pollen from anther to stigma
self = within same flower, while cross = between flowers on different plants (of same species)
- there will be little variation, so the offspring will become homozygous (1 type of allele)
- if there’s a variation, it will be a mutation but there’s a low chance that mutations will be expressed
- offspring will not be able to adapt to change in the environment
- when there’s a new disease, there’ll be a low chance of survival
Downstream processing refers to all the processes that occur to the contents of the fermenter after it is emptied. This involves making penicillin into a form that can be used as a medicine.
Suggest why downstream processing is necessary. [3]
- purifying or separating penicillin from waste or untreated substances
- needs to be pure to be used in medicines or made as food flavourings
Define the term tissue. [2]
- a group of cells with similar structures
- working together to perform a shared function
Define the term inheritance [1]
transmission of genetic information from generation to generation
Define the terms gene and gene mutation. [2]
gene a length of DNA that codes for a protein
gene mutation a change in BASE sequence of DNA
key terms for enzyme questions
opt temp (denature), active site, complementary shape, tertiary structure, enzyme substrate complex, reactant and product
A flower grower bred red carnations. Describe how growers selectively breed plants. [3]
- breed parent plants with DESIRED feature
- chose offspring for desired feature(s)
- cross (offspring) plants showing features with each other
- many generations of crossing and selecting ;
define the term meiosis. [2]
nuclear division
chromosome number is halved
(diploid to) haploid
results in genetically different cells / gamete
Genes for fur colour black, orange and mix of two
Explain why coat colour is an example of discontinuous variation. [3]
distinct phenotypes
no (continuous) range of colour
controlled by genes
not affected by the environment
state the function cartilage in the gas exchange system. [2]
- forms incomplete rings around trachea / bronchi
- keeps airways open
- protects (trachea) airways
- sound production in larynx
which comes first in binomial naming system, genus or species?
genus
Discuss advantages of sexual reproduction to a wild population of flowering plants. [5]
- gives genetic variation
- alleles / genes from different plants / parents
- pollen exchanged between individuals / cross pollination
- allows mutations to be expressed
- allows adaptation to changed environment
- (new species) can evolve / allows natural selection to occur
- can colonise new areas
- less competition (with parent plant / among offspring) ;
State two structural features that distinguish the cells of a protoctist from a prokaryote [2]
- nucleus / nuclear membrane envelope (named) organelle / internal membranes
- cell walls (if present) have different composition
- linear chromosomes
suggest why DNA can be used to identify individual people. [2]
individual people have, different / unique, DNA ;
DNA has genes or alleles have sequences of bases
endoplasmic reticulum function
- site of protein synthesis
- assemble amino acids in a specific sequence to make protein
Explain how sewage treatment reduces the spread of disease. [3]
- removal of, harmful bacteria /pathogens from sewage, like cholera bacteria
- stop spread of pathogens via water
- use of chlorination / chemical treatment
Explain the importance of nitrifying bacteria in the nitrogen cycle. [3]
- conversion of ammonia to nitrate (ions)
- convert ammonium ions to nitrite ions
- make nitrate ions available to plants
- nitrate ions are absorbed by plants
- nitrate ions are used to make amino acids / proteins
Describe how growers selectively breed plants. [3]
- breed parent plants with DESIRED features
- choose offspring for desired feature
- cross those offsprings
- for several generations
Define the term species. [2]
group of organisms that can reproduce to produce a fertile offspring
Define the term sustainable development. [2]
development that provides for the needs of an (increasing) human population
without harming the natural environment / ecosystems
Define the term allele. [1]
a version of a gene
treatment for severe diarrhoea. [1]
oral rehydration therapy
state two examples of larger molecules found in cells that are made from amino acids. [2]
- proteins
- polypeptides = antibodies, insulin, haemoglobin, glycogen
Describe how the students could measure their breathing rates.[2]
- watch chest rise and fall
- in one minute
Before starting the investigation, the researchers confirmed that the woman did not have
coronary heart disease..
Suggest why. [1]
Explain why exercise is recommended for people with a high risk of developing coronary
heart disease. [3]
safety risk (not to over exercise) ;
CHD could change the expected result (for healthy people) ;
- prevents blocked arteries
- lowers blood pressure
- lowers cholesterol
- weight loss
- lower (resting) pulse
Describe the events that occur after pollen grains leave the anther of a flower until fertilisation takes place. [5]
- pollen lands on stigma
- pollen tube grows
- through style
- to ovary
- (pollen nucleus / male gamete) enters ovule
- through micropyle
- pollen and ovule NUCLEI fuse
carbon dioxide highest (immediately) after exercise, decreases;
falls below resting level
Describe and explain the results of the investigation shown in Fig. 2.2 [6]
2/ [3] marks for that description of graph
- removal of excess carbon dioxide
- more energy used during exercise means higher rates of respiration
- aerobic respiration releases carbon dioxide
- oxygen not supplied fast enough (from lung / heart) / more oxygen required by
muscles ; - oxygen debt, so
- anaerobic respiration (in muscles), which produces lactic acid
- lactic acid is broken down to glucose
Describe and explain how drug affects the function of the relay neurone. [3]
- drug X blocks receptor (molecules)
- neurotransmitters are not able to bind to receptor (molecules)
- drug X is similar in complementary to shape of receptor (molecule)
- drug X stops impulse being transmitted in relay neurone ;
- (so) less / no, pain felt with drug X
Injected into body
State two other ways that HIV can be transmitted [2]
(contaminated) blood transfusion
sexual fluids
breast feeding
blood to blood contact
Describe how shunt vessels and arterioles are involved in maintaining a constant internal body temperature. [3]
- vasoconstriction of arterioles
- shunt vessels dilate
- less blood flow to skin capillaries
- reduces heat loss from blood
Compare development of foetus in the early stages of pregnancy to its development in the late stages of pregnancy. [2]
Describe functions of amniotic fluid and amniotic sac. [4]
- growth and development during all stages
- (more) increase in complexity in early stages ;
- (more) increased in size in later stages
- maintains temperature ;
- (mechanical) protection
- provides support (of the fetus) ;
- provides a sterile environment
- lubrication
- allows movement (of the fetus) ;
(movement) allows for development of bones and muscles ;
Explain why farmers use herbicides. [2]
Suggest how herbicides damage ecosystems in a lake. [4]
Herbicide B is a chemical that prevents the uptake of magnesium ions. Suggest how B kills plants. [3]
to increase crop yield / production ;
to reduce competition with weeds
- kills water plants / algae
- lack of, producers / food for herbivores
- bioaccumulation
- reduced biodiversity ;
- (lack of roots causes) erosion / flooding
- chlorophyll cannot be synthesised
- cannot trap sunlight
- cannot photosynthesise
State two features that distinguish leaves of dicotyledonous plants from leaves of monocotyledonous plants [2]
network / branched, veins
broad (leaves)
petiole
In 1839 Charles Darwin published a book that described differences in a family of birds called
finches.
Each species of Galápagos finch had:
• a different diet
• a different beak shape
Galápagos finches share a common ancestor.
Suggest how Galápagos finches have evolved different shaped beaks [5]
Due natural selection
there was variation as a result of mutation
The birds with unique beak shape were more likely to find food and survive
Birds that survived reproduced offspring beaks like them
They passed on their alleles and continued over many generations, evolving different shaped beaks
How can a breeder determine the genotype of… [2]
Carry out DNA testing or perform a test cross
Test cross is by breeding with homozygous recessive (king cheetah)
If any of the offspring of the test cross are [king cheetahs it confirms 17 is heterozygous]
suggest why cheetah is at risk of becoming endangered. [3]
- hunting by humans,
- loss of (natural) habitat,
- pollution
- infection by a disease
- lack of food / prey
- climate change
Comparing graphs
overall trend
higher graph
gradient
interesting point (e.g. line B reached 0 earlier)
comparative data (initial)
what is essential for making chlorophyll
magnesium ions
questions about natural selection pattern
- variation
- mutation
- selective advantage
- survived and reproduced
- passed on their alleles
- continued over many generations
translocation of transpiration for water and sucrose?
sucrose = tranlocation
water = transpiration
define a sense organ
groups of receptor cells
responding to specific stimuli ;
define active transport [2]
movement of ions through the cell membrane
against concentration gradient
using energy from respiration
explain how dialysis machine filters blood. [4]
describe the advantages of a kidney transplant compared to dialysis. [3]
why is it important to match tissue type of donor and recipient/ [1]
- dialysis membrane is partially permeable
- minerals, ions urea, move by diffusion
- from high concentration to low concentration / down a
concentration gradient ; - water, moves by osmosis, (osmosis is the movement of water) from high water potential to low water potential across membrane
- proteins / blood cells too large to move across membrane
- glucose is not removed by dialysate (same concentration)
- fresh dialysate maintains a concentration gradient ;
fewer diet / fluid intake restrictions ;
no need for regular visits to hospital ;
less unwell / tired / nausea / headaches / less pain (after surgery) ;
no needles / no fistula, permanently in arm
avoid rejection
aerobic respiration equation
C6H12O6 + 6O2 -> 6CO2 + 6H2O
xerophytes and hydrophytes
xerophytes = dry , cacti
hydrophytes = wet, water lily
describe how fertility drugs improve the chances of getting pregnant. [3]
FSH/clomid injected early in the menstrual cycle
inhibit action of oestrogen
stimulate production of FSH and makes sure FSH levels are high enough
stimulate egg production
menstrual cycle
muscle in uterus wall contracts
amniotic sac breaks
cervix dilates
baby passes out of vagina
umbilical cord is ties and cut
afterbirth
state the function of villi [1]
absorption (of digested food / water) / movement of (small) molecules (from
small
intestine) into blood ;
where is bile secreted
liver and gall bladder
where is lipase and trypsin secreted
pancreas
Explain the advantages of presenting information about food webs as a pyramid of biomass and not as a pyramid of numbers [3]
in a pyramid of numbers one large individual is shown in the same way as
one very tiny individual
- biomass indicates how much food there is, available
- biomass is an indicator of the energy available ;
pyramid of biomass is pyramid shaped whereas a pyramid of numbers is not always
Water absorbed by the roots moves through the stem and enters the leaves. Most of this
water is lost in transpiration.
Explain how the internal structure of leaves results in the loss of large quantities of water in transpiration. [3]
xylem supplies water ;
air spaces ;
large (internal) surface area ;
water evaporates from surface of mesophyll cells ;
guard cells, open / close, stomata ;
water vapour, diffuses out through stomata
Explain the mechanism that increases blood flow through the skin
detection by, sensory neurone (in skin)
brain / hypothalamus, as control centre
impulses in, motor / effector, neurones ;
MUSCLES in shunt vessels contract, so shunt vessels, constrict
arterioles dilate / vasodilation ;
increased / more, blood flow, into capillaries / near surface (of skin) ;
explain the importance of regulating body temperature in humans.
(so that) enzymes do not denature
- maintain a constant rate of, reactions
- avoids to damage to other named (type of) protein ;
avoids damage to cell membranes ;
avoids, heatstroke / hyperthermia / overheating / dehydration
/ freezing, hypothermia ;
at high temperature sperm production, reduced / harmed ;
Explain why the sex of a child is determined by its father. [2]
sex is determined by X and Y chromosomes / males are XY and
females are XX
egg cells have X chromosome
sperm cells have X or Y chromosome
chromosome / only males can provide the Y chromosome ;
Explain how teeth decay occurs [4]
named) food remains on teeth ; 4 bacteria, use / breakdown, sugars / carbohydrate / sweet foods ;
respiration ;
acid is produced ;
© UCLES 2020
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for (named) enzyme action / chemical digestion ; AVP ; e.g. mix food with saliva
acid, dissolves / erodes / destroys / wears away / AW, enamel ; dentine is exposed / AW ;
dentine, softer / dissolves more rapidly (than enamel) ;
AVP; e.g.decayreachesnerveendingsleadingtopain
