Exam questions I got wrong

Question 1

what bond forms between two nitrogenous bases holding two polynucleotide chains together?

Answer 1

hydrogen

Question 2

what ion is required for the hydrolysis of starch by an enzyme?

Answer 2

cl-

Question 3

ventilation is a process involving various parts of the body.
describe the movement of ribcage and external intercostal muscles and the diaphragm during exhalation

Answer 3

ribcage moves inwards and downwards
eternal intercostal muscles contract
diaphragm contracts

Question 4

how is colorimeter calibrated?

Answer 4

distilled water to set it to zero

Question 5

name the bond in a tertiary structure protein that holds two cysteine amino acids linked?

Answer 5

disulphide

Question 6

what immunity does a vaccine provide?
natural or artificial?
active or passive?

Answer 6

artificial active

Question 7

is adenine a pyrimidine?

Answer 7

NO a purine

Question 8

Tubilin protein found in all eukaryotes and some prokaryotes.
explain how genetic code in gene of tubulin codes for the protein tubule?
(2 marks)

Answer 8

genetic code degenerate , 3 amino acids code for more than one protein
base sequences determine the sequence of amino acids

Question 9

what image colour does a scanning electron microscope display?

Answer 9

black and white

Question 10

what image colour does a laser scanning confocal microscope display?

Answer 10

colourful

Question 11

what colour of image does a transmission electron microscope display?

Answer 11

black and white

Question 12

dna can be extracted from white blood cells. an enzyme is used during this process, what enzyme and why?

Answer 12

protease to break down histones wrapped around the DNA

Question 13

why would standard deviation error bars increase confidence in a conclusion made about a graph?

Answer 13

spread of data used rather than mean
reduced likely affect of anomaly

Question 14

one advantage of using binomial name for species?

Answer 14

see evolutionary link between species

Question 15

explain importance of maintaining biodiversity for the discovery of new antibiotics?

Answer 15

. many drugs made come from plants
. increase chance of developing a new drug

Question 16

definition of personalised medicines?

Answer 16

using genes of individual for medicine

Question 17

definition of synthetic biology?

Answer 17

synthesis of new genes

Question 18

how do you work out percentage uncertainty?

Answer 18

uncertainty / measured value

Question 19

suggest and explain reasons why in the 21st century only 10% of the gene loci are polymorphic in wild populations of cheetah? 3 marks

Answer 19

. gene pool become small due to hunting and disease
. fewer alleles
. reduced genetic diversity

Question 20

out of these two option A or B , what describes a property or function of cholesterol?
A: increases fluidity of phospholipid bilayer at high temperatures
B: It is an unsaturated fatty acid because it contains carbon-carbon double bonds

Answer 20

B

Question 21

describe expiration at rest

Answer 21

external intercostal muscles and diaphragm relax and the rib cage moves down and in

Question 22

what option is NOT a component of a chloroplast?
A. crisate
B. DNA
C. Ribosome
D. Thylakoid

Answer 22

A

Question 23

explain using examples of transported substances why multicellular plants need transport systems?

Answer 23

. plants have a small surface area to volume ratio
. sucrose needs to be transported from source to sink - assimilate
. diffusion pathway distance too great

Question 24

outline how properties of water are essential for sustaining life on earth?

Answer 24

1. water universal solvent , polar molecule and contains hydrogen bonds
2. water has adhesive and cohesive forces help water molecules stick together to provide tensile strength in plants
3. water is translucent (clear) help sunlight to pass through, allowing plants to photosynthesise
4. ice provides a habitat for polar bears

Question 25

out of skeletal , cardiac or involuntary muscle, which one has tired and is branched and interconnected?

Answer 25

cardiac

Question 26

is skeletal or cardiac muscle multinucleated?

Answer 26

skeletal

Question 27

what are four proteins?

Answer 27

actin myosin tropomyosin troponin

Question 28

use your knowledge of the sliding filament model of muscle contracts, explain why the image (you don't have but its contracted) presents a contracted muscle? 3 marks

Answer 28

1. sarcomere shortens 2. bands are not overlapping 3. think filament shortened

Question 29

after death, the concentration of ATP in muscle cells decreases . during this time the muscles become rigid in the process. suggest why a lack of ATP would lead to muscle rigidity? 2 marks

Answer 29

ATP needed to break cross bridges to detach myosin from actin prevents relaxation of muscles

Question 30

describe the different sources of ATP that is used in muscle contraction during strenuous exercise. 6 marks

Answer 30

1. aerobic respiration occurs when oxygen available (1) which produced greater yield of ATP (1) 2. oxygen limited during strenuous exercise (1) 3. the glycolysis stage will be used during anaerobic respiration (1) and NAD is regenerated for glycolysis to continue (1) 4. ATP free in sarcoplasm in muscle cells (1)

Question 31

during testing different temperatures in fish on oxygen rate , using a respirometer. what are two precautions to take to ensure the results obtained are valid? 4 marks

Answer 31

1. use appropriate temperature (1) range to avoid stress to the fish (1) 2. allow the temperature to be reached to required point (1) before taking measurements to allow the fish to acclimatise (1)

Question 32

how do you work out Q10?

Answer 32

R1 / R2

Question 33

suggest why the cells that produce digestive enzymes are described as exocrine rather than endocrine? 1 mark

Answer 33

released into ducts

Question 34

suggest the location receptors for steroid hormones, that are lipid soluble.

Answer 34

on plasma membrane - phospholipid bilayer - because inside cell

Question 35

what is a role of cortisol?

Answer 35

regulates carb metabolism

Question 36

a symptom of adrenal failure is low blood pressure and a salt craving, what can cause this?

Answer 36

lack of aldosterone

Question 37

what part of the pancreas produces adrenaline only?

Answer 37

medulla

Question 38

the hormone ACTH is produced by the pituitary gland , what part of the pancreas does ACTH only affect?

Answer 38

adrenal cortex

Question 39

explain what is meant by pluripotent?

Answer 39

stem cells that can differentiate into all cell types except the placenta

Question 40

what are some weaknesses of using adult stem cells? 2 of them

Answer 40

accumulate mutations increased risk of cancer