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Biology Past Paper Common
Questions By Vasumitra
Gajbhiye
Chapter 1 Define species. (group of) organisms that can reproduce to produce fertile offspring. Define sensitivity. the ability to detect or sense stimuli in the internal or external environment ; and to make appropriate responses Define growth increase in, size/ length/mass / volume/AW ; increase in cell number ; Define organ. structure made up of a group of tissues, working together to perform a specific function(s) ; Define the term sense organ. groups of receptor cells ; responding to specific stimuli ; How bacteria differ from other from other groups of organisms? cell wall, peptidoglycan/murein no nucleus/ no nuclear membrane/ have nucleoid
loop of DNA no mitochondria no chloroplast no vacuoles smaller ribosomes have pili have capsule small State features that all prokaryotes have. cytoplasm; cell membrane; single celled / unicellular; no (true) nucleus / no nuclear membrane; loop of DNA / chromosome / naked DNA; no, (membrane-bound) organelles / mitochondria / chloroplasts; (peptidoglycan / murein) cell wall; AVP; e.g. plasmids State structural features that distinguish the cells of a Protoctista from a prokaryote. nucleus / nuclear membrane / nuclear envelope ; (named) organelle(s) / internal membranes ; cell walls (if present) have different composition ; linear chromosomes ; What are other names for protists? protoctists protoctista
Chapter 3 Explain what happens to the cell of a leaf cause wilting. ref to osmosis water, lost from the cells down water potential gradient pressure of water on the cell wall decrease turgor pressure decrease plants/ cells rely on water for support/ to prevent wilting water in cells not being replaced as quickly (as it is being lost) Suggest the advantages to a plant of wilting. stomata closed to prevent water loss water conserved for other processes decrease surface area, exposed to the sun. What happens during plasmolysis?
- cytoplasm/ vacuole, decreases in, size/ volume ;
- (some) cell membrane/ cytoplasm, pulls away /AW, from cell wall ;
- plasmolysis / cells are plasmolyzed ;
- cells, are flaccid/ not turgid/ lose turgor ;
- cell walls no longer, pushed outward/withstand pressure ; Why plant cells don’t burst? Cell wall offers resistance. State features of diffusion that do not apply to active transport. passive/ does not require energy ; substances move down a concentration gradient ; does not have to occur across a membrane ;
occurs with gases ; no need for protein, carrier/ channels /pumps ;
Chapter 4 What is the benefit of having less fat in diet? less cholesterol less risk of atherosclerosis/ blockage of arteries/ atheroma/ stroke/ CHD less risk of heart attack/ heart diseases less risk of obesity less calorie intake What is the benefit of having more fiber in diet? there is less risk of constipation (prevents) less risk of colon/ bowel cancer fiber absorbs and removes toxins. Describe the similarities between marasmus and kwashiorkor. both caused by protein (energy) deficiency ; both types of malnutrition / deficiency disease / caused by lack of a balanced diet ; primarily affects children ; diarrhoea ; low body mass / weight loss ; poor growth ; irritability / tiredness ; wastage of muscles ; dry skin / brittle nails ; brittle hair / change of hair colour ;
- enzymes are specific;
- (enzymes are) catalyst / speeds up reaction;
- lowers (activation) energy needed for the reaction;
- successful collisions;
- active site;
- (enzyme and substrate) fit together;
- (enzyme and substrate) complementary shape / AW;
- enzyme-substrate complex / ESC;
- ref. to optimum, temperature / pH;
- too much heat results in denatured enzymes;
- too little kinetic energy / heat, less (successful) reactions;
- incorrect pH results in denatured enzymes Define the term catalyst. (substance) that increases the rate of (chemical) reactions ; not changed, during / by, the reaction
Chapter 6 Describe the use of carbohydrates in plants. cellulose ; for cell walls ; starch ; for energy/respiration ; to attract insects to flowers / nectar / fruits ; Describe the use of amino acids in plants. to make (named) proteins ; for enzymes ;
for growth ; Explain how gravitropism enables a plant to survive (roots / plants growing down) anchor the plant / AW ; (roots / plants growing down are more likely) to reach, water / (named) minerals ; (shoots / plants) growing up are more likely to reach light ; (shoot or plant has better) access to (named) pollinators ; Describe ways in which palisade mesophyll cells are adapted. contain many chloroplasts / lots of chloroplasts ; are tightly packed ; are located near the top of the leaf ; arranged ‘on end’/ vertically / lengthways / columnar ; Explain why some parts of a plant can act as both a source and a sink. source when it is (moving sucrose from) a region of production / photosynthesising ; sink when it is, growing / storing / respiring / a region of utilisation ; Explain how roots are adapted to absorb ions. root hair (cells) ; through carrier molecules /AW ; large/ increased, (surface) area (for absorption) ; roots grow continually (to find new sources of ions) ; AVP ; e.g. extensive root network / branching roots ; Why increase in temperature increase rate of photosynthesis. temperature is a limiting factor ; increases, (kinetic / heat) energy / the movement of molecules / diffusion ; more collisions between substrate and enzymes ; to speed up chemical reactions ;
inflammation/ soreness of tongue brittle nails unusual craving for non-nutritive substances, such as ice, dirt or starch poor appetite tingling or crawling feeling in legs. What is the cause of sickle cell anaemia? Mutation change in base sequence in gene for haemoglobin. Different sequence of amino acids. Inherit the allele. Having the recessive allele produce, abnormal haemoglobin red blood cells have sickle shape Explain how people with sickle-cell anaemia inherit the disease. both parents carry the, recessive allele/ allele for (sickle cell) anaemia both parents are heterozygous half the gametes of both parents have the recessive allele people/ children, who are homozygous recessive have (sickle cell) anaemia. there is is 25% chance of being homozygous…. ….recessive / having (sickle cell) anaemia The distribution of sickle-cell anaemia is the result of natural selection. Explain the distribution of the sickle-cell allele in human population. people with sickle cell anaemia/ heterozygous/ carriers/ are resistant to, malaria people with (homozygous) sickle cell anaemia are, less likely to survive/ die of sickle cell disease.
people who are heterozygous are more likely to survive/ have selective advantage they are more likely to breed pass on allele for sickle cell so increase in frequency of sickle cell allele (in population) selective advantage for sickle cell only exists where, (mosquitoes carrying) malaria are present AVP; ref to evolution/ adaptation to (local) condition Sickle-cell anaemia is a disease that reduces the delivery of oxygen to tissues. Explain why. haemoglobin is, abnormal / rigid / AW ; abnormal haemoglobin carries less oxygen (than normal haemoglobin) ; red blood cells are, sickle shaped / AW ; (sickle cells) stick together / clot (in blood vessels) ; fewer red blood cells ; Describe the effects of diarrhoea on the body. watery faeces dehydration loss of, salts / ions / electrolytes cramps / stomach pain death What is meant by double circulation. one loop to lungs/ pulmonary circulation, and one loop to rest of the body/ systemic circulation blood flows through heart twice, for one (complete) circuit/ to get back to the same point. What are the advantages of double circulation.
needed for (growth / development / strengthening of) bones ; needed for (growth / development / strengthening of) teeth ; prevents rickets ; Explain why iron is important? required to make haemoglobin / red blood cells ; for transport of oxygen ; prevents (iron-deficiency) anaemia ; Explain why vitamin C is important? helps with, cell / tissue, repair / healing ; helps to reduce risk of (named) infection / AW ; formation of, collagen / hair / nails anti-ageing of skin antioxidant prevent scurvy improves (named) mineral ion absorption required for protein synthesis Describe the effects of vitamin D deficiency in humans. muscle cramps; soft / bent, bones / rickets; stunted growth; prone to infections; fatigue; reduced ability to absorb calcium (ions); What are the causes of Kwashiorkor? not enough protein (in the diet) ; adequate energy (in the diet) ;
inadequate diet after breast feeding finishes / AW ; Explain how cholera causes diarrhoea. cholera / pathogen, releases/ produce toxin ; toxins attach to the wall of the small intestine ; toxin causes chloride secretion into small intestine ; lowering water potential in the intestinal lumen ; causing osmotic movement of water into the gut / water flows from, the cells / blood, into the, lumen / gut ; ref. to, osmosis / movement of water (into the lumen) ; (diarrhoea is) loss of watery faeces ; loss of salts / loss of minerals dehydration ; Define chemical digestion. breakdown of large molecules to small molecules ; from insoluble to soluble ; Define the term assimilation. movement of digested food molecules into cells ; food molecules become part of cells ; Explain the role of mechanical digestion. breaks up food into small(er) pieces ; without chemical change ; by teeth / muscles ; to mix (with digestive juice) ; increases surface area ; for enzyme action ; speeds up chemical digestion ;
transports, fats / fatty acids, into, lymph(atic) vessels / lymph(atic) system / lymph ;
Chapter 8 Explain how transpiration occurs in leaves? water evaporates from the surface of mesophyll cells water vapour diffuses through the stomata out of the leaf Explain the mechanism that is responsible for the movement of water in xylem vessels. evaporation from (cell walls) in mesophyll ; diffusion of water vapour through stomata ; reduction of, pressure / water potential, at top (of plant) resulting in water moving upwards; continuous column of water (in the xylem) ; cohesion of water (molecules) ; cohesion described as, forces / attraction, between water molecules ; transpiration pull ; water enters or leaves xylem, by osmosis / down water potential gradient ; Explain the role of phloem in plant transport. translocation (phloem) allows bidirectional movement movement of food from source to sink sucrose/ amino acids/ food are produced at a source region of respiration/ growth/ storage is a sink
named example of a source/ sink (when photosynthesising leaves are source and roots are sink) some organs can be both a source or a sink at different times. Explain how xylem is adapted for its function. Functions conduct / transport, water (and mineral ions) ref to transpiration ; reduced resistance to water flow / AW ; ( structural) support (for plant) ; prevents (inward) collapse (of xylem vessels) (spirals) allows (some) flexibility / bending, of stems (to prevent breaking)
Adaptations long / elongated (cells / vessels / tubes) ; ref to lignin (in walls) ; (cell walls) are water impermeable / waterproof / AW to prevent water loss ; (secondary) thickening of cell walls ; hollow / no cytoplasm / no (named) organelles ; no, end / cross, walls (between cells) ; end plates to connect vessels (end to end) ; pits in walls (for water movement between vessels) ; State structural features of xylem vessels and explain how this is related to the function of water transport. thick / strong, (cell) wall ; withstanding, tension / collapse / hydrostatic pressure / AW ; lignin (in walls) / walls are impermeable ; prevents collapse / waterproofing ;
4 plant cannot produce enough, glucose / photosynthesise fast enough ; 5 weeds cannot maintain rate of growth ; 6 AVP ; e.g. falls over and can’t absorb sunlight Explain how auxins control the growth response. (auxins is a hormone) made / produced, in (shoot), tip / apex ; pass / move / diffuse / spread (down the stem) ; auxins collect in the side, in the dark / away from light ; stimulates greater cell elongation on side in the dark ; AVP e.g. absorption of water (by osmosis) / stretching of cell walls / phototropic(s) / plants detect or sense light / ref to turgor pressure Describe and explain how root hair cells are adapted for their function. long and thin; thin cell wall; large surface area; for absorption; (water by) osmosis ; (ion / nutrients by) active transport; against the concentration gradient; protein (pumps) in membrane; require energy / ATP; ref. to many mitochondria; What is the function of stomata? for gas exchange / diffusion of gases ; for, photosynthesis / respiration / transpiration ;; correct gas with direction for named process ;; controls the rate of, diffusion / transpiration / photosynthesis ;
ref. to transpiration pull ; Outline how water that has entered a root hair cell reaches the stomata. 1 water moves from root cells, into xylem ; 2 cohesion / adhesion AW, of water molecules ; 3 (this) pulls on/ creates tension (in water column in xylem) ; 4 Water moves up/ through, the xylem ; 5 mass flow of water (in xylem)/ transpiration stream ; 6 water moves into leaf by osmosis (from xylem) ; 7 loss of water from leaf (cells) lowers water potential ; A ref to water potential gradient 8 evaporation, from surfaces of (mesophyll) cells / into air spaces (in leaf) ;
Chapter 9 How CHD is caused? fat is deposited in the walls of coronary arteries arteries are blocked/ blood flow is restricted in arteries less/ no, blood blow to, heart muscles/ cardiac muscles/ wall of heart less/ no, nutrients/ glucose/ oxygen, reaches heart, muscle/ walls/ cells. How CHD is treated? Drugs treatment to lower blood pressure. or prescribe aspirin to reduce risk of blood clotting. coronary by pass operation can be done a piece of blood vessel attached/ joined to carry blood around the blocked artery angioplasty can be done balloon inserted into artery and inflated using water to widen artery. stents. small mesh can also be inserted (into artery) to hold the artery open
