Yr12 Mock Exam Qs Flashcards
Explain how the heart muscle and the heart valves maintain a one way flow of blood from the left atrium to the aorta (5)
Atrium has higher pressure than ventricle (due to filling / contraction) causing atrioventricular valves to open;
Start anywhere in sequence, but events must be in the correct order.
1. Accept bicuspid, reject tricuspid
1. Allow: blood passes through the valve = valve open / blood stopped from passing through the valve = valve closed
- Ventricle has higher pressure than atrium (due to filling / contraction) causing atrioventricular valves to close;
- Ventricle has higher pressure than aorta causing semilunar valve to open;
Points 1, 2 and 3 must be comparative: eg higher 3. Allow aortic valve
4. Higher pressure in aorta than ventricle (as heart relaxes) causing semilunar valve to close;
4. Allow aortic valve
- (Muscle / atrial / ventricular) contraction causes increase in pressure;
Name two biological molecules that can be coded for by a gene.
Do not include a polypeptide or protein in your answer.
(Pre) mRNA
tRNA
rRNA
Fill in the gaps.
ATP synthase comprises several polypeptides, so is said to have
a ________ structure.
It catalyses the synthesis of an ATP molecule by a ________ reaction; this involves the ____________of a water molecule. The ATP synthase in Figure 1 is in a mitochondrion so would catalyse reactions during ______ _________.
Quaternary
Condensation/phosphorylation/redox
Release/loss/formation
(Aerobic) respiration;;
As shown in Figure 1, ATP synthase has two functions. • ItcatalysesthesynthesisofATP.
• It allows the movement of H+ions.
Suggest how the shape of the ATP synthase allows it to have these two functions.
Explain your answers.
- catalyses the synthesis of ATP
- allows movement of H+ ions
(Catalysed the synthesis of ATP)
1. Active site complementary to ADP + Pi;
2. Enzyme-substrate complex forms;
(Allows the movement of H+ ions)
3. Channel (in membrane/protein/enzyme);
4. Allows facilitated diffusion of H+
galacto-oligosaccharides (GOS) are polymers of galactose.
Explain why GOS are described as polysaccharides.
Galactose is a monosaccharide/monomer;
2. (Polysaccharide is a) carbohydrate polymer;
3. (Several) monosaccharides/monomers/galactose joined by condensation reactions
OR
(Several) monosaccharides/monomers/galactose joined by glycosidic bonds;
Give two differences between the structures of GOS and lactose.
Lactose contains (alpha) glucose and GOS does not
Lactose contains (alpha)glucose + galactose and GOS contains only galactose;
Lactose is a disaccharide and GOS is a polysaccharide;
Lactose has one glycosidic bond and GOS has many glycosidic bonds
Explain why amylase produced in the human digestive system does not digest GOS.
- active site is NOT complementary to starch
- due to TERTIARY structure
Prebiotics are foods used to promote good health in humans.
Prebiotics stimulate the growth of ‘healthy’ bacterial populations in the human digestive system.
The bacteria in these ‘healthy’ populations produce enzymes that hydrolyse GOS
Suggest how GOS can work as a prebiotic.
- provide galactose / sugars
- used in respiration
- used in binary fission
Stroke volume = volume of blood leaving a ventricle with each contraction Cardiac output = stroke volume × heart rate
Use all the information to describe what causes the increase in cardiac output:
• fromresttomedium-intensityexercise
• from medium-intensity exercise to high-intensity exercise.
You do not need to calculate cardiac output to answer this question.
Rest to medium-intensity exercise
Medium-intensity exercise to high-intensity exercise
[2 marks]
Rest- medium= stroke volume and heart rate INCREASES
Medium- high= heart rate INCREASES
Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise.
[3 marks]
ARTERIOLE
- muscles relax
- vasodilation increases blood flow
Scientists have produced a mutated rice variety in which there is no crossing over.
A population of the mutant rice variety produced by sexual reproduction shows genetic variation. Populations of non-mutant rice varieties also show genetic variation.
Suggest and explain the similarities and differences in the causes of genetic variation within these rice populations. (3)
- independent segregation = genetic variation
- both have further mutations
- crossing over causes variation in non-mutant only
Describe the hydrolysis reactions involved in the digestion of triglycerides. Do not write about the activity of lipase. (2)
BREAKING of ester bonds
By addition of water
2 All mammals produce a lipase called CEL. CEL digests triglycerides.
CEL is activated by bile salts binding to the enzyme.
Describe two other functions of bile salts. (2)
Emulsify lipids/fats
Increases surface area
Form micelles
Mammals feed their young on milk. CEL digests the triglycerides in milk. The ability to produce CEL occurred due to a gene mutation.
Describe how natural selection may have led to all mammals in a population producing CEL. (4)
Mutation leads to a new allele
Those with new allele can digest milk/ triglyceride
Individuals with CEL are more likely to survive and reproduce
Directional selection
Increase in frequency of allele in population
Use your knowledge of the cell cycle to explain the results shown in Figure 4. (3)
Mass of DNA in 1 = interphase/ G1
Mass of DNA in 2= mitosis
Mass of DNA in 1 and 2= some DNA has been replicated
