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
