Paper 1 Exam Qs

Question 1

A heartbeat sound is described as ‘lub-dub’ what happens during the ‘lub’ at ventricular systole

Answer 1

atrioventricular valves close and blood leaves the ventricles

Question 2

what monosaccharides are made from the breakdown of sucrose

Answer 2

alpha glucose
fructose

Question 3

the enzyme microtubule depolymerase breaks down the spindle fibres in mitosis - at what stage will there be the most active enzymes

Answer 3

telophase

Question 4

what is atrial fibrillation

Answer 4

irregular and rapid rate

Question 5

summarise chloride shift

Answer 5

hydrogen carbonate ions movin out of red blood cells and chloride ions moving into red blood cells

Question 6

state 2 differences between ADP and a DNA nucleotide

Answer 6

ADP has 2 phosphates WHEREAS DNA nucleotide has 1 phosphate
ADP has ribose WHEREAS DNA nucleotide has deoxyribose

Question 7

ADP binds with a Pi to make ATP - what type of reaction is this

Answer 7

condensation (phosphorylation)

Question 8

explain how the genetic code in the gene for a protein codes for that protein

Answer 8

3 bases code for amino acid
sequence of bases determines sequence of amino acids
code is non overlapping

Question 9

explain how to calculate a diameter of the nucleus using a light microscope

Answer 9

use eyepiece graticule
calibrate eyepiece graticule with stage micrometer
measure the diameter in eyepiece graticule units
take repeat measurements and calculate a mean

Question 10

using a transmission electron microscope, it was concluded that a WBC had stopped dividing at the G2 checkpoint - state 2 observations that would have led to this conclusion

Answer 10

no visible chromosomes
nuclear membrane present

Question 11

during the DNA extraction practical, why do WBCs not need to be crushed before adding detergent

Answer 11

they have no cell wall to break

Question 12

why is detergent used in DNA extraction

Answer 12

breaks down the phospholipid bilayer

Question 13

what type of enzyme should be used in this practical

Answer 13

protease which breaks down histones

Question 14

why would using standard deviation error bars improve confidence in a conclusion

Answer 14

SD shows spread of data compared to the mean
so reduces the effect of anomalies

Question 15

suggest 3 reasons for an increase in antibiotic resistance over 5 years

Answer 15

not completing course of antibiotics
overprescription of antibiotics
natural selection

Question 16

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

Answer 16

plants are an important source of drugs
so maintaining biodiversity increases the chance of finding new drugs
maintains genetic resource for the future

Question 17

define synthetic biology

Answer 17

synthesis of new genes

Question 18

what is the function of DNA polymerase

Answer 18

make phosphodiester bonds between adjacent nucleotides

Question 19

define ectopic heartbeat

Answer 19

an extra or early heartbeat that is out of the normal rhythm of the heart

Question 20

which bond is not formed when a conjugated protein folds into its quaternary structure

Answer 20

peptide

Question 21

explain why nuclear division in a zygote is mitosis not meiosis

Answer 21

mitosis for growth of zygote
which needs genetically identical cells
not meiosis as gametes arent produced

Question 22

explain the role of embryonic stem cells in the development of the embryo

Answer 22

embryonic cells are undifferentiated
so can differentiate into any cell type

Question 23

describe and explain why collagen is a fibrous protein

Answer 23

it is a long chain of amino acids
insoluble
it has little tertiary structure

Question 24

suggest why collagen is such a strong molecule

Answer 24

it has many H bonds
and many covalent bonds

Question 25

outline the method of chromatography that will separate the main amino acids in collagen

Answer 25

digest collagen into amino acids and place sample on chromatography paper on pencil line dry and repeat place chromatography paper in solvent

Question 26

describe the structure of the rough endoplastic reticulum

Answer 26

phospholipid bilayer forms cisternae covered with ribosomes membrane is continuous with nuclear envelope

Question 27

explain the role of the membrane in the rough endoplastic reticulum

Answer 27

compartmentalisation holds ribosomes in place separates synthesised proteins from cell cytoplasm

Question 28

describe how a potometer could be used to calculate an accurate rate of transpiration

Answer 28

potometer should be airtight dry the leaves cut shoot with a slanted cut measure distance air bubbles have travelled in 60 secs calculate volume of water uptake maintain temp and light intensity

Question 29

describe the symplast pathway

Answer 29

water travels through the cytoplasm and plasmodesmata to reach the xyelm

Question 30

explain how the nucleotides in a DNA molecule are arranged as 2 polynucleotide strands

Answer 30

nucleotides are joined together by phosphodiester bonds hydrogen bonds between complementary bases polynucleotides are antiparallel