BIOLOGY

Explain the advantages of the type of circulatory system found in humans, compared with the circulatory system shown in fish

efficient removal of carbon dioxide and lactic acid, separation of oxygenated and deoxygenated blood, efficient supply of blood, lower pressure in the lungs, provides higher pressure in the body which allows a high rate of respiration

what is nitrification

process that converts ammonia to nitrite and nitrite to nitrate

what is denitrification?

process by which nitrate is reduced to nitrogen gas under anaerobic conditions

explain the process of deamination

removal of nitrogen containing part of amino acids

urea is formed

explain the process of eutrophication

1 untreated sewage / fertiliser / nutrients ;

2 increased availability of nitrates / ions / AW ;

3 causing algal bloom / algae reproduction ;

4 algae reduce (penetration of) sunlight (in the water) / AW ;

5 (so rooted) plants unable to photosynthesise ;

6 so plants die ;

7 bacteria, decompose / feed, on dead, plants or algae ;

8 so bacterial populations increase ;

9 bacteria respire aerobically ;

10 bacteria use up the oxygen in the water ;

11 organisms / fish , die / suffocate / migrate, due to lack of oxygen ;

Describe the function of the prostate gland in the male reproductive system.

fluid / semen, for the sperm / male gametes, to swim

Explain how sweating helps a person to maintain a constant internal body temperature

glands in the skin produce sweat ;

sweat on (the surface of) the skin evaporates ;

using / AW, heat / energy (from the body) ;

(internal) body temperature, decreases / returns, to a set point ;

ref. to homeostasis / negative feedback

explain how mRNA is involved in protein synthesis.

(mRNA) is a copy of the gene / DNA / base sequence ;

gene / DNA, remains in the nucleus ;

(mRNA takes instructions) to cytoplasm / ribosome ;

mRNA, passes through / attaches to / ‘read by’, ribosome ;

base sequence determines sequence of amino acids (in the protein) ;

Describe what is meant by the term physical digestion.

the breakdown of food into smaller, pieces

without chemical change (to the food molecules) ;

Discuss the advantages of intensive livestock production.

1 less land required / AW, (than extensive farming) ;

2 (so) fewer trees cut down / less deforestation ;

3 more land available for named use ;

4 improved yield ;

5 more efficient named farming practice ;

6 cheaper (named), products / food / meat / milk ;

7 idea of consistent, quality / growth, of product ;

8 increased food security ;

9 (increased) profits (for farmer)

One disadvantage of intensive livestock production is that antibiotics are often used.

Suggest why antibiotics are needed in intensive livestock production.

treat / prevent, (spread of) bacterial, disease / infection ;

caused by close proximity / overcrowding / AW ;

Explain the development of antibiotic resistance in bacteria.

ref. to (resistance due to) mutation ;

2 antibiotics kill non-resistant bacteria / resistant bacteria survive ;

3 (resistant bacteria / bacteria that survive the antibiotic) reproduce ;

4 passing on alleles (for resistance) ;

5 idea that over time this increases, the proportion of population of bacteria

that is resistant / frequency of resistant allele ;

6 ref. to natural selection ;

Explain how a scientist could determine if different crop plant species share a recent ancestor (are closely related

use, base / amino acid / nucleotide / gene, sequences OR sequence,

DNA / RNA / AW ;

2 (crops with) recent ancestors / closely related species, will have more,

sequences / genes / alleles in common / will have similar,

sequences / genes / alleles ;

State factors that can increase the risk of coronary heart disease

diet OR a diet high in, salt / saturated fats / cholesterol ;

2 (uncontrolled) stress ;

3 smoking (tobacco) ;

4 genetic (predisposition) ;

5 (old) age ;

6 sex ;

lack of exercise

whats the chemical control of the plant that is responsible for phototropism

auxin ;

2 (auxin) is made in / released from, the (shoot) tip ;

3 (auxin) moves by diffusion from (the shoot tip) ;

4 (auxin) is concentrated on, shaded / left / AW, side of the, shoot / plant ;

5 (auxin) stimulates cell elongation ;

6 shaded / left / AW, side of shoot, elongates / bends / grows, more than,

light / right, side ;

reasons why the energy decreases between trophic levels

(energy lost as) heat / respiration ;

(named other) metabolic processes ;

(energy lost in) movement / muscle contraction ;

not all of the organism is, eaten ;

not all of the organism is digested or (energy lost in) faeces / egestion ;

not every organism in that trophic level is eaten

Describe the advantages of representing food chains using a pyramid of energy compared with a pyramid of biomass.

more accurate representation of energy, transfer / loss ;

idea of accounts for (different) rate of reproduction ;

idea of accounts for (different) life spans ;

idea of accounts for different, sizes / body composition, of organisms ;

idea of accounts for, time / seasonal variations ;

allows (better) comparisons between ecosystems

Suggest reasons for this species of plant to use self-pollination rather than cross-pollination.

lack of (named) pollinators ;

2 idea that plant is isolated / AW ;

3 uses less, pollen / energy ;

4 increased chance of, fertilisation / pollination / offspring ;

5 idea of (less genetic diversity is) beneficial if plant is well-adapted to its

environment ;

Discuss the potential effects of only using self-pollination in a population of plants.

less / no, genetic variation ;

2 less likely to, survive / adapt to, changes in the environment ;

3 less resilience against disease / disease spreads more quickly ;

4 (increased risk of) extinction ;

5 ref. to likelihood of genetic disease ;

sources of genetic variation in populations.

meiosis

random mating

mutation

random fertilization

describe mitosis and its role in organsisms

1 ref. to nuclear division ;

2 production of genetically identical cells ;

3 (copies of / replicated) chromosomes separate ;

4 chromosome number is maintained (in each daughter cell) / AW ;

5,6 named roles of mitosis

Describe what is meant by the term excretion.

removal of waste products of metabolism ;

and substances in excess (of requirements)

ways that amino acids are processed in the liver

deamination

assimilation

Outline how the base sequences in DNA control cell function.

base sequences of DNA / mRNA) determine sequence of amino acids ;

amino acids form proteins / protein synthesis / production of proteins ;

named example of protein ;

ref. to sequence of amino acids determining protein shape ;

Explain how inspiration occurs.

1 diaphragm, contracts / flattens / lowers ;

2 external intercostal muscles contract (and internal intercostal

muscles relax) ;

3 ribs / ribcage, lifted / AW, up / out / forwards ;

4 increase the volume, in the thorax / lungs / chest ;

5 decreasing the pressure, in the thorax / lungs / chest ;

6 air is drawn in to equalise the pressure (between atmosphere and

lungs

Suggest why scientists breed the GM crop plants for many generations

1 to check (that the GM crops) inherit / have / express, gene / allele

(to produce insect resistance) ;

2 to check (that the GM crops) have the same / a high enough

yield / good (described) quality product / AW ;

3 to check (that the GM crops) can grow in, intended / different

environments / AW ;

4 to check the gene / allele / GM / crop / plant, does not cause any

unexpected / unwanted, effects / AW ;

5 idea of building up a large quantity of, seed / plants / crops (to sell

to farmers) ;

Describe how a gene can be transferred from one organism to another using genetic modification.

section of DNA / gene / allele, is isolated / cut / AW(from one

organism's chromosome / DNA) ;

2 restriction enzymes used (to cut / isolate, gene / DNA / plasmid) ;

3 bacterial plasmid DNA and section of (one organism's)

DNA / gene, cut with the same (restriction) enzyme ;

4 sticky ends formed (when restriction enzymes are used) ;

5 (sticky) ends / base pairs (of bacterial plasmid DNA and other

organism DNA) are complementary ;

6 section of (one organism's) DNA / gene / allele, is inserted into

(bacterial) plasmid (DNA) ;

7 (DNA) ligase used (to insert, gene / DNA, into plasmid) ;

8 recombinant, plasmid / DNA, is formed (when, gene / DNA, and

plasmid are joined) ;

9 (recombinant / plasmid, DNA) inserted into, bacteria / another

cell / organism ;

10 AVP; multiplication / reproduction / division / growth, of (GM)

bacteria OR use of a fermenter for (GM) (for multiplication of

bacteria) OR protein from (one organism's) gene / allele,

made / expressed, in (GM) bacteria

State advantages of GM crops

confer resistance to,

herbicides / pesticides / disease / salinity / cold / hot / drought / wind

(e.g. thicker stems) / heavy metals ;;

3 provide additional, nutrients / AW (to humans) ;

4 improved, yield / shelf life (of product) / flavour / quantity /

appearance / AW ;

5 reduced pollution OR less / no, use of, fertiliser / pesticides ;

describe the role of chemical digestion

(the breakdown) of large molecules into small molecules ;

idea of (only) small molecules can be absorbed ;

idea of insoluble (molecules) to soluble (molecules)

Explain the mechanism that links the increase in physical activity to the changes in breathing

1 increased carbon dioxide in blood ;

2 (high) carbon dioxide (in blood) detected by the brain ;

3 increases impulses to (named) muscles used in breathing / AW ;

4 increases contraction of (named) muscles used in breathing ;

5 adrenaline is released ;

6 to increase rate and depth of breathing

function of chloroplast

traps light energy ;

transfers energy from light into energy in chemicals ;

(energy) for the synthesis of (named) carbohydrates ;

It is important to try and limit the development of antibiotic resistance.

Describe ways of limiting the development of antibiotic resistance.

only use for bacterial infections / when essential / when necessary ;

use appropriate antibiotic ;

Explain how deforestation can contribute to an increase in global temperatures.

1 decrease in photosynthesis leads to less carbon dioxide removed from atmosphere ;

2 increase in decomposition of trees leads to more carbon dioxide added to the atmosphere ;

3 increase in combustion of trees leads to more carbon dioxide added to the atmosphere ;

4 carbon dioxide traps, infrared / long wavelength, radiation (from the ground) ;

5 increase / enhanced, greenhouse effect ;

Describe other undesirable effects of deforestation.

1 loss of habitat ;

2 extinction of species ;

3 reducing biodiversity ;

4 disrupt cycling of nutrients ;

5 disrupt, energy flow / food web / food chain ;

6 loss of possible, fuels / crop plants / drugs / genes ;

7 soil erosion / infertile land ;

8 (more run off) flooding ;

9 (fewer trees means) less transpiration / less water vapour in the

atmosphere ;

10 so less rainfall / droughts / desertification ;

importance of water in the body

1 ref to solvent / described ;

2 for digestion / named example ;

3 for excretion / named example ;

4 for transport / named example ;

5 temperature regulation ;

6 support, cells / tissues ;

Describe the functions of the placenta and the umbilical cord shown

1 maternal and fetal blood are kept separate / AW ;

plus any three from:

2 umbilical cord / placenta, transfers named substance, from mother / to

fetus ;

3 umbilical cord / placenta, transfers named substance, from fetus / to

mother ;

4 umbilical cord / placenta, transfers, antibodies / passive immunity, from

mother / to fetus ;

5 placenta forms barrier to, toxins / pathogens ;

6 placenta secretes, progesterone / oestrogen

Describe the functions of the amniotic sac and amniotic fluid.

1 protects, (fetus) against (mechanical) damage ;

2 regulation of temperature ;

3 allows fetus to move / allows muscle or bone development ;

4 protects fetus from infection / provides antibodies ;

5 allows lung development ;

6 sac produces amniotic fluid

Describe what is meant by the term producer.

(organism) makes its own (named organic) nutrients ;

using energy from sunlight / through photosynthesis ;