BMAT Biology

Question 1

monohybrid cross

Answer 1

study of the inheritance of one characteristic

mating between two organisms with different variations at one genetic chromosome of interest

Question 2

cystic fibrosis

Answer 2

recessive genetic disorder
inherited
affects lungs and digestive system

Question 3

screening of cystic fibrosis

Answer 3

newborns: heel prick test done shortly after the neonate is born, to confirm a sweat test is done (salt levels are v high in those with CF), saliva test done
antenatal: amniocentesis or chorionic villus sampling

Question 4

polydactyly

Answer 4

dominant genetic disorder
inherited
causes development of extra fingers and toes

Question 5

screening of polydactyly

Answer 5

PGD- preimplantation genetic diagnosis (only done for people having IVF), amniocentesis

Question 6

huntington’s disease

Answer 6

dominant disorder
inherited
affects neurones- degenerative
late onset

Question 7

screening of huntington’s

Answer 7

PGD, amniocentesis, heel prick test, saliva test, chorionic villus sampling

Question 8

process of genetic modification

Answer 8

1) copy of gene desired is taken from 1 organism
2) replication of desired gene
3) gene is inserted into a vector to form recombinant DNA
4) vectors transfered into another organism where it expresses the gene

Question 9

examples of genetic modification

Answer 9

plant crops

insulin production using bacteria

Question 10

process of natural selection

Answer 10

1. variation w/in species
2. causes differential survival
3. those best adapted to survive w/ adv gene reproduce
4. genes/ characteristics are passed onto next generation

Question 11

sources of variation

Answer 11

genetic, environmental, combined

Question 12

how does extinction occur

Answer 12

if organisms do not adapt quickly enough e.g climate change causing mass extinction

Question 13

role of protease, lipase and amylase in digestion

Answer 13

protease- digests proteins into amino acids (called pepsin in stomach)
lipase-digests lipids into glycerol and fatty acids
amylase- digestion of carbohydrates into monosaccrides

Question 14

respiration

Answer 14

the chemical process used to release energy

Question 15

aerobic respiration

Answer 15

glucose + oxygen –> carbon dioxide + water

Question 16

anaerobic respiration

Answer 16

done using enzymes, doesn’t use oxygen
ANIMALS: glucose –> lactic acid (+ATP)
YEAST: glucose –> carbon dioxide + ethanol

Question 17

aerobic v anaerobic

Answer 17

aerobic: complete oxidation of glucose, products don’t have stored chemical energy, high energy release
anaerobic: partial oxidation of glucose, products have stored chemical energy, small but fast energy release

Question 18

CNS

Answer 18

brain and spinal cord

Question 19

structure and function of sensory neuron

Answer 19

send action potentials to relay neurons

have long dendrites and short axons

Question 20

structure and function of relay neuron

Answer 20

pass action potentials between neurons (sensory and motor), found in brain
have short dendrites, can have long or short axons

Question 21

structure and function of motor neuron

Answer 21

transmits action potentials away from CNS to periphery (effectors)
have short dendrites and long axons

Question 22

synapse structure and function

Answer 22

a synapse is a gap between 2 neurons

1) in in the presynaptic neuron an action potential is carried and triggers vesicles in the nerve ending to release neurotransmitters
2) the neurotransmitters diffuse across the synaptic cleft where they bind to receptor molecules on the post synaptic neuron
3) this stimulates the post synaptic neuron to transmit the action potential

Question 23

function of digestive system

Answer 23

to break down food into units that can be used for chemical reactions
the alimentary canal: mouth (has salivary glands), oesophagus, stomach, pancreas (produces enzymes-lipase protease and amylase), liver (produces bile), gall bladder (stores bile before releasing into duodenum), small intestine ( duodenum, ileum), large intestine (colon, rectum), anus

Question 24

what is peristalsis

Answer 24

movement of matter through the digestive system

uses circular and longitudinal muscles of gut wall

Question 25

digestion

Answer 25

mechanical digestion: chewing in mouth, churning in stomach
chemical: happens by action of enzymes in stomach and small intestine- duodenum

HCl in stomach provides acidic enviroment ideal for protease enzymes (pepsin) in stomach

bile neutralises acid and provides ideal alkaline environment for enzymes in small intestine, emulsifies fats increasing surface area for lipase enzymes to work on

Question 26

absorption

Answer 26

process of moving digested food molecules from the small intestine into the blood/lymph- occurs mostly in ILIUM

the small intestine wall has villi which have microvilli that increase surface area for absorption
wall is only 1 cell thick: short distance for diffusion and active transport
network of capillaries transports digested food away
lacteal (small internal structure) transports digested fatty acids and glycerol into lymph

Question 27

4 main blood groups

Answer 27

A- has A antigen on RBC, B antibody in plasma
B-has B antigen on RBC, A antibody in plasma
O- has neither A or B antigens on RBC, has A and B antibodies in plasma
AB- has both A and B antigens on RBC, has neither A or B antibodies in plasma

Question 28

what is RhD

Answer 28

RBCs sometimes have another antigen, known as the RhD antigen-you can be RhD negative or positive

Question 29

explain function of kidney

Answer 29

reabsorption of water to maintain water potential, nephron=functional unit of kidney

Question 30

how do hormones work

Answer 30

travel in blood to target organs

Question 31

what limits the length of a food chain

Answer 31

energy flow- at each trophic level energy is wasted e.g. not all matter can be consumed such as bone

Question 32

pryamid of biomass

Answer 32

a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem

Question 33

processes that occur in the carbon cycle

Answer 33

respiration, combustion, decomposition, photosynthesis

Question 34

process of nitrification

Answer 34

biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate:
NH3 to NO2- to NO3-

Question 35

process of denitfication

Answer 35

the loss or removal of nitrogen or nitrogen compounds specifically : reduction of nitrates or nitrites commonly by bacteria (as in soil) that usually results in the escape of nitrogen into the air.
Nitrates are converted into nitrogen gas.
This process is disadvantageous for the soil and plants.
This is carried out by denitrifying bacteria.
Denitrifying bacteria do not need oxygen as they are anaerobic (therefore they thrive in waterlogged soil).

Question 36

nitrogen fixation

Answer 36

Nitrogen gas is converted into nitrates by nitrogen fixing bacteria, which are aerobic
This process is quickened by the presence of oxygen and higher temperatures.
These bacteria can be found ‘free’ in the soil or in roots nodules found on the roots of plants such as peas, beans, and clover.
Within the root nodules the bacteria gain carbohydrates from the plant and the plant gains a source of nitrates in return

Question 37

process of decomposition

Answer 37

Decomposers (some free-living bacteria and fungi) break down animal and plant proteins (from dead organisms) and nitrogenous waste products to release energy. As a result of decomposition nitrogen is released into the soil in the form of ammonium

Question 38

nitrogen cycle stages

Answer 38

nitrogen fixation
feeding
excretion of nitrogenous waste
decomposition
nitrification
uptake of nitrates
denitrification

Question 39

explain emulsification of fats during digestion

Answer 39

happens in lower intestine
bile releases from gall bladder causes the fat globules to be broken down into smaller lipid droplets which increase surface area for lipase to work on BUT THE LIPID SURFACE AREA FALLS