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
Describe the behaviour of chromosomes in prophase and metaphase of mitosis. (2)
Prophase- chromosomes condense
Metaphase- chromosomes line up on equator
Blood donation involves healthy donors giving blood that can be used to treat hospital patients.
When donors arrive, the haemoglobin concentration of their blood is tested.
A sample of each donor’s blood is added to a copper sulfate solution to determine whether the haemoglobin concentration is high enough to donate.
Errors sometimes occur with this test.
Tom has a concentration of haemoglobin high enough to donate.
Lucy has a concentration of haemoglobin too low to donate.
Evaluate the consequences of errors occurring when Tom’s and Lucy’s blood samples are tested. (3)
Tom
- (healthy donor) not allowed to donate
- fewer patients treated
- Tom has anxiety about his health
Lucy
- her blood may not be safe to give
- her blood may NOT help patients
- her LOW haemoglobin goes untreated
It was surface area of every lamella.
not possible for the scientists to measure the length of every filament and the surface area of every lamella.
Suggest how they collected data to give a reliable mean for these variables (2)
Random samples
Large sample size
Outline the similarities in, and the differences between, the structures of DNA and RNA molecules. (6)
Similarities
1.Polymers of nucleotides;
2. (Nucleotide has) pentose, (nitrogen-containing organic) base and a phosphate (group);
3. Cytosine, guanine and adenine (as bases);
4. Have phosphodiester bonds;
Differences
5. Deoxyribose v ribose;
6. Thymine v uracil;
7. Long v short;
8. Double helix/stranded v single stranded;
Outline the similarities in, and the differences between, the structures of chloroplasts and mitochondria. (4)
Similarities
1. Double membrane;
2. Both contain (circular) DNA;
3. Both contain ribosomes;
Differences
4. Thylakoids/lamellae/grana v cristae;
5. Stroma v matrix;
6. Pigments v no pigments;
7. Starch grains v no starch grains;
describe the primary structure of all proteins (2 marks)
- sequence of amino acids
- joined by peptide bonds
Give the definitions of:
- ** universal
- non-overlapping
- degenerate**
(3)
universal= same codon/ triplet always codes for the same amino acid
non-overlapping= each base is only part of one triplet/codon
degenerate= more than one codon/ triplet codes for each amino acid
descrieb one difference between the structure of DNA in a prokaryotic cell and in an eukaryotic cell (1)
- circular not linear
- not associated with proteins or histones
- no introns
describe the mechanism of breathing that causes air into the lungs (3)
- diaphragm muscles contract and diaphragm flattens/pulls down
- external intercostal muscles contract and ribcage pulled up/out
- causes volume increase and pressure decrease in thoraic cavity ( below atmospheric pressure)
explain why phospholipids can form a bilayer but triglycerides cannot (3)
M1- phospholipid both hydrophobic and hydrophilic or polar or phosphate group is charged
M2- triglycerides only hydrophobic or non-polar
M3- Hydrophilic attracts water
describe the role of tRNA in translation (2)
M1- anticodon (on tRNA) binds to complementary codon on mRNA
M2- (tRNA) brings/carries specific amino acid to ribosome
describe how gas exchange occurs in single celled organisms and explain why this method cannot be used by large, multicellular organisms (3)
M1- diffusion (across cell surface membrane)
M2- Larger organisms have a LARGER SA:V
M3: Diffusion pathway would be too long
Potato plants with fewer sucrose transport proteins produce fewer potatoes and accumulate sugars in their leaves.
Explain why. (2)
M1- Carbohydrates made by photosynthesis (in the leaf)
M2- less sucrose transported to sink/potato/root
Give two reasons why glucose uptake by muscle cells increases significantly during exercise (4)
- increased respiration
- to provide more ATP for muscle contraction
- concentration gradient of glucose transporter proteins increase
- glucose enters by FD
