EQ

Question 1

Explain the function of this ATP hydrolase.

Answer 1

ATP into ADP and PI releases energy

Question 2

How does tidal volume being reduced effect exchange between co2 in blood and alveoli

Answer 2

Less carbon dioxide exhaled
So reduced concentration gradient between blood and alveoli
So more c02 remains in the blood

Question 3

Why is countercurrent flow in fish more efficient than parallel flow In humans

Answer 3

Parallel - air and blood flow in same direction so diffusion gradient decreases till reaching equilibrium until exchange can no longer occur
In fish blood flows opposite to water diffusion gradient maintained along the whole length of gill lamellae,oxygen rich water always meets oxygen rich blood and oxygen poor water always meets oxygen poor blood but has a higher oxygen cg for diffusion

Question 4

Why to plant leaves with little water grow slower according to gas exchange

Answer 4

The stomata will close so less carbon dioxide for photosynthesis

Question 5

Give the pathway red blood cell takes from travelling in the human circulatory system from kidney to lungs

Answer 5

The red blood cell travels from the renal vein to the vena cava.
It then enters the right atrium of the heart.
From the right atrium, it moves into the right ventricle.
The right ventricle pumps the blood into the pulmonary artery which carries blood to lungs for oxygen

Question 6

Mice have a large surface area to volume ratio and tend to lose heat rapidly. How does this affect their haemoglobin?

Answer 6

They have higher metabolic rates, so their haemoglobin needs to release oxygen more readily. This means their oxygen dissociation curve is shifted to the right, making oxygen unloading more efficient

Question 8

Explain four ways in which the structure of the aorta is related to its function.

Answer 8

(Aorta is an artery)
Elastic tissue recoils when ventricles relax and stretches when ventricles contract
Muscle for contraction
Thick walls withstands pressure
Smooth endothelium reduces friction
Semilunar valve prevents backflow to the heart (most arteries don’t have valves)

Question 9

explain how tissue fluid is formed. In 2 marks

Answer 9

High blood pressure causes high hydrostatic outward pressure at atrial end and reduces inward pressure at venue end of capillaries ,so tissue fluid formed

Question 10

The hydrostatic pressure falls from the arteriole end of the capillary to the venule end of the
capillary. Explain why.

Answer 10

Loss of fluid

Question 11

The water potential of the blood plasma is more negative at the venule end of the capillary
than at the arteriole end of the capillary. Explain why.

Answer 11

Water has left the capillary at the ateriole end
Proteins are to large to leave
So more plasma protein deacreases water potential

Question 12

A student determined their pulse rate when sitting down. Describe how they could have
investigated whether their results were typical of all students of their age.

Answer 12

Use a large sample size of students calculate the mean and sd,see if their mean lies with in the sd if its close to the sd it means its close to the average and not unusual

Question 13

In a healthy person, blood moves in one direction as it passes through the heart. Give two ways
in which this is achieved

Answer 13

Pressure gradient from high to low
Valves prevents backflow

Question 14

Suggest how widening of blood vessels can reduce ventricular blood pressure.

Answer 14

Wider lumen less friction so less pressure

Question 15

Some babies are born with a hole between the right and the left ventricles.
These babies are unable to get enough oxygen to their tissues.
Suggest why.

Answer 15

Mixing of deoxygenated and oxygenated blood not enough oxygenated blood from left ventricle flows into aorta

Question 16

Describe the role of haemoglobin in supplying oxygen to the tissues of the body

Answer 16

Haemoglobin binds with oxygen to form oxyhaemoglobin in areas of high partial pressure of oxygen (e.g. lungs).
It then releases oxygen in areas of low partial pressure of oxygen (e.g. tissues).

Question 18

A principle of homeostasis is the maintenance of a constant internal environment. An increase in
the concentration of carbon dioxide would change the internal environment and blood pH.
Explain the importance of maintaining a constant blood pH

Answer 18

Enzymes are sensitive to ph ,can have a change on its tertiary structure , less enzyme substrate complex formed

Question 19

How does pressure in the ventricles relate to the thickness of the walls

Answer 19

The walls contract, contraction forms pressure ,so walls must be thick to withstand this pressure

Question 20

What happens during high pressure due to high blood flow in ventricles

Answer 20

Causes valves to open in response to pressure

Question 21

Explain how the heart muscle and the heart valves maintain a one-way flow of blood from
the left atrium to the aorta.

Answer 21

When atria fill and contract it has higher pressure than ventricles causing atrioventricular valves to open blood moves to ventricles ,atrioventricular valves close after ventricles are filled as they have higher pressure than atrium ,semi lunar valves open as ventricles have higher pressure pressure than aorta , blood flows to aorta now aorta has higher pressure pressure than ventricles so semi lunar valves close to prevent backflow to ventricles

Question 22

Suggest why the pulse felt can be used to measure heart rate.

Answer 22

Caused by pressure from contraction of heart

Question 23

An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood
flow to capillaries

Answer 23

The muscle contracts narrowing the lumen

Question 24

Explain why a lack of protein in the blood causes a build up of tissue fluid

Answer 24

Water potential in cappilaries is not as low so less movement of water by osmosis

Question 25

Explain why the values for the pressure in the xylem are negative.

Answer 25

Pressure in xylem is lower than atmospheric pressure causing it to be negative

Question 26

Why is rate of transpiration pull highest at mid day

Answer 26

More stomata open Hottest at mid day more water evaporates Increases water potential gradient More tension on xylem as more water evaporates out of leaves

Question 27

The thickness of the aorta wall changes all the time during each cardiac cycle. Explain why

Answer 27

During contraction walls stretch (appears thinner )due to pressure increase, when relaxed walls recoil due to pressure deacrease This maintains pressure

Question 28

When it asks which value shows the greatest variation what do u look at

Answer 28

The one with greatest SD has greatest variation

Question 29

Why is a large sample important

Answer 29

More representative answer ,more reliable mean

Question 30

Suggest how an increase in the volume of blood entering the heart reduces angina.(disease that means not enough blood gets to heart)

Answer 30

Increases stroke volume, more oxygenated blood to heart delivered by coronary arteries

Question 31

Insects that feed on phloem don’t need to use muscles to obtain sugar why

Answer 31

Contents of phloem pushed into insects mouth under high pressure as there is high pressure in phloem vessels due to loading of sugars in leaf ,which causes water to move in by osmosis.

Question 32

One theory of translocation states that organic substances are pushed from a high pressure in the leaves to a lower pressure in the roots. Describe how a high pressure is produced in the leaves.

Answer 32

Water potential becomes more gating as sugar enter phloem ,causes water to enter by osmosis which increases pressure

Question 33

Suggest two reasons why the rate of water uptake by a plant might not be the same as the rate of transpiration

Answer 33

1. Water used for support/turgidity; 2. Water used in photosynthesis; 3. Water used in hydrolysis; 4. Water produced during respiration

Question 34

Describe how the structures of starch and cellulose molecules are related to their fun

Answer 34

Starch-helical so compact Insoluble won’t affect wp Branched glucose easily released for respiration Cellulose-long straight unbranched chains of beta glucose Joined by hydrogen bonding to form fibrils provides high tensile strength for cell wall

Question 35

Give two ways in which the structure of starch is similar to cellulose.

Answer 35

Polysaccharides,made of carbon hydrogen oxygen,have glycosidic bonds

Question 36

Explain why the transpiration rate increases when the temperature increases.

Answer 36

Molecules have more KE water evaporates more as temp increases

Question 37

Explain the relationship between the number of leaves removed from the plant shoot and the mean rate of water uptake

Answer 37

fewer stomata; 3. Less evaporation / transpiration; 4. Less cohesion / tension / pulling (force);

Question 38

What does the mean show

Answer 38

Variation around the mean

Question 39

Explain how the structures of the walls of arteries and arterioles are related to their functions

Answer 39

Elastic tissue stretches and recoils under pressure when heart beats and relaxes Which evens out pressure. Muscular contraction reduces the size of the lumen controlling flow Epithelium is smooth reduces resistance

Question 40

Describe how water is moved through a plant according to the cohesion-tension hypothesis.

Answer 40

1. water evaporates / transpires from leaves; 2. reduces water potential in cell / water potential / osmotic gradient across cells (ignore reference to air space); 3. water is drawn out of xylem; 4. creates tension (accept negative pressure, not reduced pressure); 5. cohesive forces between water molecules; 6. water pulled up as a column;

Question 41

Use your knowledge of leaf structure to explain why less water is lost through the upper surface of leaves than is lost through the lower surface

Answer 41

Thicker waxy cuticle on upper surface Less stomata on upper surface

Question 42

Some xerophytic plants have sunken stomata. Explain the advantage of this adaptation.

Answer 42

Reduced water potential gradient so reduce rate of transpiration

Question 43

A stem was cut from a transpiring plant. The cut end of the stem was put into a solution of picric acid, which kills plant cells. The transpiration stream continued. Suggest an explanation for this observation.

Answer 43

Xylem is made of dead cells,transpiration is passive

Question 44

Explain how the cuticle reduces water loss.

Answer 44

Impermeable prevents water passing through

Question 46

Renal Artery

Answer 46

Brings oxygenated blood to kidney for filtration

Question 47

Renal vein

Answer 47

Bring filtered deoxygenated blood away from kidney to inferior vena cava

Question 48

Hepatic atery

Answer 48

Supplies oxygenated blood from heart to liver

Question 49

Hepatic vein

Answer 49

Drain deoxygenated blood from from liver to inferior vena cava

Question 50

Hepatic portal vein

Answer 50

Brings nutrient rich blood from digestive system to liver for processing

Question 51

Describe how 2 amino acids defer from one another

Answer 51

Have dif r groups

Question 52

Describe structure of proteins

Answer 52

Made of amino acids formed by condensation reactions joined by peptide bonds Primary structure is order of amino acids; Secondary structure is folding of polypeptide chain due to hydrogen bonding; alpha helix / pleated sheet tertiary structure is 3-D folding due to interaction between r groups hydrogen bonding and ionic / disulfide bonds; Quaternary structure is two or more polypeptide chains.

Question 53

Describe how proteins are digested in human gut

Answer 53

Hydrolysis of peptide bonds; Endopeptidases break polypeptides on inside of chain into smaller peptide chains; Exopeptidases hydrolyses peptide bonds at terminal amino acids; Dipeptidases hydrolyse dipeptides into amino acids

Question 54

Describe the role of haemoglobin in supplying oxygen to the tissues of the body.

Answer 54

Forms oxyhaemaglobin Binds to oxygen at areas of high partial pressure e.g exchange surfaces Unloads at areas of low partial pressure e.g muscle cells

Question 55

What is a transcription factor?

Answer 55

A molecule that moves from the cytoplasm to dna

Question 56

What is a codon?

Answer 56

Three bases on mRNA

Question 57

What is the role of RNA polymerase during transcription

Answer 57

Join rna nucleotides to form pre mRNA

Question 58

mRNA can be converted to cDNA. Name the enzyme used in this process."

Answer 58

Reverse transcriptase used to convert mRNA into complimentary dna

Question 59

During which part of the cell cycle are gene mutations most likely to occur? And why

Answer 59

Interphase This is when dna replication occurs errors during copying of dna

Question 60

Meiosis also occurs during the life cycle of organisms. What is the importance of meiosis

Answer 60

To produce gametes so that after fertilisation diploid number can be restored and genetic variation will be introduced to organism

Question 61

instruction. “Push down hard on the cover slip, but do not push the cover slip sideways. ” Explain why she was given this instruction.

Answer 61

To spread/squash tissue Do make sure cells to roll together

Question 62

How can I conclude from a diagram cell in anaphase

Answer 62

Chromatids being pulled to poles by spindle attached to centromere V shaped sister chromatids show pulling apart of chromatids at centromere

Question 63

What do u say when it asks u to describe the appareance of a chromosome

Answer 63

2 sister chromatids held by a centromere due to dna replication

Question 64

What happens in meiosis during cross over

Answer 64

Crossing over exchange of alleles between homologous chromosomes

Question 65

Homologous chromosomes carry the same genes but they are not genetically identical.Explain

Answer 65

They have different alleles

Question 66

Describe how DNA is replicated.

Answer 66

Strands separate / H-bonds break; 1. Accept: strands unzip 3. Both strands / each strand act(s) as (a) template(s); 4. (Free) nucleotides attach; 5. Complementary / specific base pairing / AT and GC; Hydrogen bonds also reform 6. DNA polymerase joins nucleotides (on new strand); 8. Semi-conservative replication / new DNA molecules contain one old strand and one new strand;

Question 67

Explain how the doctor could have recognised which cells were in interphase when looking at the tissue samples

Answer 67

Nucleus visible No visible chromosomes

Question 68

When will the dna amount be 8.4 and when 4.2

Answer 68

8.4-late interphase,prophase metaphase , anaphase 4.2-telophase as cells divided

Question 69

Why for light microscope do we need one cell thick

Answer 69

Single later of cells for light to penetrate

Question 70

Why would plants that reproduce sexually be variable in their yield

Answer 70

Gametes are formed by meiosis in which crossing over occurs giving genetic variation between plants and some plant have genes to produce higher or lower yield

Question 71

Describe and explain the processes that occur during meiosis that increase genetic variation.

Answer 71

Homologous chromosomes pair up Independent segregation occurs where parental and maternal chromosomes are re shuffled in any combination Crossing over leads to exchange of alleles between homologous chromosomes Both create new combinations of alleles

Question 72

Meiosis process

Answer 72

Chromosomes duplicates to have 2 sister chromatids Homologous chromomes pair up Crossing over homologous chromosomes exchange alleles Independent segregation homologous chromomes line up randomly Maternal and parental chromosomes go into daughter cells randomly Homologous chromomes separate in to 2 cells Sister chromatids separate now four haploid cells formed

Question 73

Describe and explain how the structure of DNA results in accurate replication.

Answer 73

2 strands for semi conservative replication Both strands act as a template strand Base pairing and hydrogen bonds hold strands together Hydrogen bonds can be separated easily so DNA can be copied A with T c with g

Question 74

Why is inhalation active but exhalation passive

Answer 74

Inhalation -muscles contract diaphragm moves down intercostal contracts Exhalation-passive unless exercise , diaphragm relaxes and intercostal relaxation (during quiet breathing the intercostal only contract during extercise or blowing out) lungs recoil due to elastic tissue pushing air out without muscular effort