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WorksheetsOCR A Level Biology
Total questions: 135
Worksheet time: 2hrs 15mins
Which of these structures contains RNA but not DNA?
nucleus
mitochondrion
chloroplast
ribosome
Which of the following is a function of the Golgi apparatus?
to aid endocytosis
to make proteins from amino acids
to synthesise ATP
to make secretory products
What is the name given to the structures which penetrate the walls of adjacent plant cells?
middle lamellae
plasmodesmata
pits
channels
Cells in culture will absorb amino acids from the surrounding culture medium. If radioactively labelled glycine is provided in the culture medium, in which organelle will radioactivity be found first?
ribosomes
nucleus
lysosomes
Golgi apparatus
What resolution can be achieved with a light microscope?
20μm
2μm
0.2μm
0.02μm
Intestinal epithelial cells have observable “brush borders” seen on the cells. What are they?
microvilli
cilia
flagella
villi
What are centrioles involved in?
lysosome formation
intracellular digestion
ribosome formation
cell division
The (a) is responsible for the destruction of damaged cells?
Which of the following is concerned with the synthesis and transport of lipids and steroids in the cell?
Rough ER
Smooth ER
Golgi
Lysosome
When mitochondria are extracted from cells, they are usually kept in a 0.25 mol dm-3 sucrose solution.
What is the purpose of the sucrose solution?
it prevents the mitochondria from changing structure
it acts as a source of food for respiration
it is used as a solvent
it maintains a constant pH by acting as a buffer
Some organelles are bounded by a single membrane whilst others have two membranes. Which of the options, A – D, is correct?
A
B
C
D
Which of the following would be found in an animal cell undergoing mitosis but not in a plant cell undergoing mitosis?
chromosome
centriole
splindle
chromatid
Which of the following is absent from prokaryotic cells?
plasmids
cells wall
rough er
ribosomes
Which one of these organelles always contains DNA?
ribosome
golgi
mitochondrion
lysosome
Which process produces mRNA from DNA
Translation
Transcription
Transcribtion
DNA replication
What base does RNA have instead of Thymine?
(a)
In which organelle does translation occur?
Nucleus
Golgi apparatus
Ribosome
SER
What are the 3 bases on a tRNA molecule that bind to the mRNA called?
base triplet
anticodon
codon
intron
In eukaryotic cells, pre-mRNA is spliced to remove (a) .
Which enzyme forms mRNA?
RNA transcriptase
DNA polymerase
DNA transcriptase
RNA polymerase
What does the 't' of tRNA stand for?
translation
transfer
transplant
tryinghard
Which of these statements are TRUE about tRNA (select ALL that apply)
It carries a specific amino acid
It is single stranded
It has hydrogen bonding
It is less stable than mRNA
What is the cellular proteome?
Range of proteins produced by a cell
The main protein produced by a cell
All of the proteins coded for in a cell
All of the proteins produced by an organism
Which of these are features of the genetic code (select ALL that apply)
The code is degenerate
The code is overlapping
The code is universal
There are stop codons
Which definition of the magnification of a drawing of a leaf is correct?
the actual size of an object multiplied by the magnification of the microscope
he difference in size between an actual object and a drawing of the object
the increase in size of an object when observed using a microscope
the size of the drawing of a specimen in comparison to the actual size
Which labelled features identify these cells as eukaryotic?
W, X and Y
W and X only
W only
X only
Plant cells are fixed, stained and viewed using a student microscope. The light source was natural light. What would be clearly visible at ×400 magnification?
cristae of mitochondria
grana of chloroplasts
nucleoli
ribosomes
Some secretory cells synthesise and release glycoproteins. What is the correct order of the sequence of events as they occur in the secretory cell?
1 exocytosis
2 product accumulates in secretory vesicle
3 mRNA binds to ribosomes
4 synthesis of glycoprotein
3, 4, 1, 2
3, 4, 2, 1
4, 3, 1, 2
4, 3, 2, 1
Which statement describes how the molecular structure of starch is suited to its function?
Amylose has a branched structure and amylopectin is coiled to give a compact molecule for transport.
In the breakdown of amylose and amylopectin, many condensation reactions release stored energy.
In the formation of amylose and amylopectin, many hydrolysis reactions allow the release of stored energy.
The amylose-amylopectin complex is insoluble and does not affect the water potential of the cell.
Cows and whales are mammals that produce milk to feed their babies. Newborn whales grow faster than newborn cows. The milk of both cows and whales contains saturated fatty acids with different chain lengths. The table shows the percentage of saturated fatty acids of different lengths in cow and whale milk.
Which statement about the ratio of short fatty acids (4–16 carbons) to long fatty acids (18 or more carbons) in the milk of cows and whales is correct?
The ratio in cow milk is higher because young cows need more energy than young whales.
The ratio in cow milk is lower because young cows need less energy than young whales.
The ratio in whale milk is higher because young whales need less energy than young cows
The ratio in whale milk is lower because young whales need more energy than young cows.
Bacterial cells divide by a process called binary fission. Which macromolecules must be synthesised for binary fission?
1 cell membrane proteins and RNA
2 DNA and peptidoglycan
3 enzymes and cellulose
1, 2 and 3
1 and 2 only
2 and 3 only
3 only
A student carried out experiments to investigate the effect of enzyme concentration on the rate of hydrolysis (break down) of protein in milk.
When the enzyme and milk were mixed, the protein was hydrolysed and the mixture changed from cloudy to clear. The student investigated five different enzyme concentrations and recorded the time taken to reach the end-point for each.
What is an appropriate control for this investigation?
Carrying out a further experiment where the enzyme solution is replaced with water.
Carrying out each experiment in a thermostatically regulated water-bath at 35 °C.
Performing three repeat experiments for each of the five enzyme concentrations.
Using the same volume of enzyme solution for each of the five experiments.
What determines the specificity of an enzyme?
1 the bonding between R groups of the polypeptide
2 the optimum pH of the enzyme
3 the peptide bonds between amino acids of the polypeptide
4 the shape of the substrate molecule
1, 2, 3 and 4
1 and 3 only
1 only
2, 3 and 4 only
The graph shows the effect of temperature on the rate at which the enzyme in a biological washing powder digests and removes fruit juice stains.
Which statements explain the shape of the graph at temperatures higher than X?
Bonds are broken between the R groups of the amino acids in the polypeptide chains of the enzyme.
There are more collisions between the enzyme and its substrate.
The tertiary structure of the enzyme is altered.
The shapes of the active site and the substrate are no longer complementary.
Which statement about the behaviour of chromosomes during mitosis is correct?
They attach to the spindle fibres to contain them within the nucleus
They condense to prevent further translation of genes.
They reach the poles of the cell and become longer and thinner.
They replicate to produce sufficient DNA to form two new nuclei.
What is the smallest unit of a DNA molecule that can be altered by a mutation and cause a change to the coding of a polypeptide?
base
codon
gene
nucleotide
The diagrams represent transverse sections of three plant organs.
A
B
C
D
Which statements about water movement in plants are correct?
1 Water can pass through cellulose cell walls.
2 Water can pass through lignified cell walls.
3 Water cannot pass through suberin in cell walls.
1, 2 and 3
1 and 2 only
1 and 3 only
2 and 3 only
The contraction of the heart is coordinated through electrical impulses passing through the cardiac muscle. Which is the correct order of part of the sequence of these impulses?
A right and left atria → sinoatrial node → atrioventricular node → ventricular walls
B sinoatrial node → right and left atria → atrioventricular node → Purkyne tissue
C sinoatrial node → right and left atria → Purkyne tissue → atrioventricular node
D sinoatrial node → right and left atria → Purkyne tissue → ventricular walls
A
B
C
D
The graph shows oxygen dissociation curves of adult oxyhaemoglobin in different carbon dioxide concentrations, 1 and 2.
Which conditions could change the shape of curve 1 to the shape of curve 2?
high carbon dioxide concentration causing a decrease in pH
high carbon dioxide concentration causing an increase in pH
low carbon dioxide concentration causing a decrease in pH
low carbon dioxide concentration causing an increase in pH
Which characteristic of the human gaseous exchange surface and the lungs, maintains the necessary concentration gradients for carbon dioxide and oxygen?
good ventilation of the lungs
large surface area of the alveoli
low resistance to air flow
the walls of the alveoli are thin
A student carried out four tests for biological molecules on a solution. The observations are shown in the table.
Which molecules may be present in this solution?
glucose, starch, protein
lipid, protein, glucose
protein, starch, sucrose
starch, protein, lipid
Which description is correct?
A collagen molecule has a high proportion of the amino acid glycine, which has a very small side chain
A group of three collagen fibres forms a strong, insoluble coiled structure termed a triple helix
Each of the collagen polypeptides in a collagen molecule has a regular spiral arrangement of many alpha helices.
Peptide bonds are present between amino acids of the same polypeptide and between the different polypeptides forming the collagen molecule.
The graphs show the rate of reaction of an enzyme-catalysed reaction.
Which graph shows the effect of increasing the concentration of the substrate at two different concentrations of a competitive inhibitor?
A
B
C
D
The diagram shows the transport of ions across the cell surface membrane.
Inside the cell there is a low concentration of sodium ions (Na+ ) and a high concentration of potassium ions (K+ ). Outside the cell there is a low concentration of K+ and a high concentration of Na+ .
The carrier molecule is a pump which exchanges Na+ for K+ .
A
B
C
D
The diagram shows transverse sections of two plant structures.
A
B
C
D
Two species of animal are found in the same area of forest and grassland. In the spring and summer they eat the same plant food.
However, in the autumn and winter one eats nuts in the forest and the other eats roots on the grassland. Both species are preyed upon by the same predator. Numbers of root-eating animals are reduced most by this, but they recover faster since they reproduce faster.
What can be concluded about these two species of animals?
1 They are part of the same community.
2 They are at different trophic levels.
3 They occupy different habitats.
4 They have different niches.
1, 2 and 4
2, 3 and 4
1 and 2 only
1 and 4 only
Name this structure
double helix
nucelotide
twisted ladder
hydrogen bond
If one strand of DNA says GCT, the other strand says:
GCT
CTA
CGA
TCG
What is the function of deoxyribonucleic acid?
store genetic information
store energy (long-term)
store energy (short-term)
build skin, hair, nails, muscles
What are the parts of a nucleotide?
phosphate, sugar, base
A, T, G, C
Nucleic Acids
two base pairs connected
The 'backbone' or 'ribbon' of the DNA strand is made of:
phosphate and sugar
phosphate only
phosphate and base
sugar and base
How many hydrogen bonds form between the bases A and T in the DNA double helix?
(a)
How many hydrogen bonds form between the bases C and G in the DNA double helix?
(a)
What type of bond holds together the sugar-phosphate backbone of nucleic acids?
phosphodiester bonds
glycosidic bonds
hydrogen bonds
peptide
The two polynucleotide strands of DNA run in opposite directions; they are said to be (a)
What is the charge on a phosphate group?
Negative
Positive
Which elements make up nucleotides?
C, H, O and N
C, H, N, S
C, H, N, O, P
C, H, O, P
How many carbon atoms make up the sugar part of a nucleotide?
(a)
Adenine is a....
purine
pyrimidine
How many phosphate groups make up a molecule of ATP?
(a)
Thinking about bond making and bond breaking, does the hydrolysis of ATP release more energy than is required, or does it require more energy than is released?
Hydrolysis of ATP releases more energy forming new bonds than is required to break bonds
Hydrolysis of ATP requires more energy to break bonds than is released in forming new bonds
What does ADP stand for?
(check your spelling)
(a)
Which enzyme catalyses the formation of ATP from ADP?
ATP synthase
ATP hydrolase
The following statements are about the structure of DNA.
Which is / are true?
Statement 1:Purine bases pair with pyrimidine bases.
Statement 2:Phosphodiester bonds link adjacent nucleotides.
Statement 3:There are always equal amounts of adenine and guanine.
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
Which of the following processes involves the formation of ester bonds?
1. synthesis of polynucleotides
2. synthesis of triglycerides
3. synthesis of polypeptides
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
Which of the diagrams of nucleotides contains uracil?
A
B
C
D
A study was carried out on butterflies in two different habitats in the north of England. The two habitats were farmland and mixed deciduous woodland.
· Surveys were completed in 1992 and then at four year intervals.
· Data were collected from butterfly transect sites in both habitats. Using this data, the total butterfly population in each habitat was estimated.
· In 2012, the general populations of butterflies in these two habitats reached historical lows as a result of the prolonged cold and wet weather.
· Between 1992 and 2012 the woodland had become overgrown due to lack of active management.
In particular the number of open spaces in the woodland had decreased.
The data in the graph shows the total butterfly populations per square kilometre in both habitats between the years 1992 to 2012.
Calculate the total percentage decrease in the number of butterflies on farmland between 1992 and 2012.
Give your answer to the nearest whole number.
(a)
The following statements compare the number of butterflies on the farmland and in the woodland between 1992 and 2012.
Which statement is incorrect?
The number of butterflies in the farmland stays higher than in the woodland
The number of butterflies in farmland has a greater decrease (than those on farmland)
From 2004 to 2012 they both fall by a similar rate
The woodland population decreases by 23% more than the farmland
The following statements are suggestions for the difference in the rates of decline of butterfly numbers in woodland and farmland.
Both habitats experienced the same weather conditions.
Between 1992 and 2012 the woodland had become overgrown due to lack of active management.
In particular the number of open spaces in the woodland had decreased.
Which statement does not provide a valid suggestion based on the information you have been given (the information given at the start is repeated below)
The woodland population dropped because of a new predator
Farmland population decreased because there's more open spaces for breeding sites
Farmland population decreased because of a lack of conservation of hedgerows and areas for wild plants to grow
Woodland population decreased because of deforestation
In 2012, the general populations of butterflies in both habitats reached historical lows as a result of the prolonged and cold weather.
A student made the following statement:
'These data (the graph) show that the change in butterfly numbers was caused by changes in weather conditions in England'
The following statements are comments on the validity of the student's statement.
Select the correct statements.
The statement lacks validity because weather conditions only refer to 2012
The statement lacks validity because numbers were falling before 2012
The statement lacks validity because weather conditions and butterfly decline may not be linked
All of the above
Select two variables from the list below that scientists should control when carrying out butterfly surveys such as this
Sample at the same time year/ same time of day
Temperature
Same sampling technique
pH
A different study was carried out on butterflies in two habitats in the North of England. The two habitats were farmland and mixed deciduous woodland.
Butterfly species in severe decline on farmland include gatekeeper, large skipper, small copper, wall brown, small tortoiseshell and white-letter hairstreak.
Butterfly species in severe decline in woodland include brown argus, common blue, gatekeeper, holly blue, marbled white, meadow brown, peacock, small copper, small heath, small tortoiseshell and wall brown.
Select from the list below to say which habitat you expect to have greater species richness and why
Woodland because there is a greater number of species in decline than on farmland (so probably more species present originally)
Woodland because there is likely to be little or no pesticide use compared to farmland
Farmland because it has lost fewer butterfly species so probably a larger number of species remain
Farmland because of hedgerow conservation meaning more niches for butterflies to occupy
Female silver-washed fritillary butterflies, Argynnis paphia, are usually an orange-brown colour. However, a deep olive-green colour can be seen in some females, largely in the south of England.
What is the term given to this type of biodiversity?
(a)
Which of the following statements describe benefits to the species of genetic biodiversity?
Colour variation is an adaptation to the environment
Reduces variation for natural selection
Some of the species will survive if a new disease is introduced
Camouflage in different habitats
What is the concentration of oxygen in water?
1%
20%
0.01%
80%
How many pairs of gills does a fish have?
1
2
3
4
What are the 'ridges' (which increase surface area) on gill filaments called?
lumen
lamellae
alveoli
leaves
Which term is used to describe the opposite flow of blood and water across gills?
(a)
Which layer of cells in a leaf carries out the most photosynthesis?
spongy mesophyll
epidermis
waxy cuticle
palisade mesophyll
What is the name of the cells which control the opening of stomata?
(a)
Which of the following are features found in xerophytes?
rolled leaves
sunken stomata
leaf hairs
lots of stomata
Which surface of a leaf generally has the most stomata?
lower
upper
In which habitats can xerophytes be found?
deserts
tundra
salt marshes
sand dunes
Which of the following are xerophytes?
oak trees
cacti
geranium
marram grass
During child birth a woman's body over produces a hormone called oxytocin until the baby is born. What kind of feedback loop would this be?
Negative Feedback Loop
Positive Feedback Loop
Neutral Feedback Loop
Linear Feedback Loop
When you are hot, your body sweats to cool you down. This means your temperature went above normal and your body sweats to counteract that change to bring you back to normal. What kind of feedback loop would this be?
Negative Feedback Loop
Positive Feedback Loop
Neutral Feedback Loop
Linear Feedback Loop
The 4 parts of the communication pathway to maintain homeostasis listed in order are:
target, sensors, control center, communication system
communication system, sensors, target, control center
sensors, control center, communication system, target
target, control center, sensors, communication system
These detect changes in the environment
Control Center
Sensors
Communication System
Target
This takes the messages from the sensors and is known as the control center
Brain
Kidney
Liver
Heart
Messages from the brain are sent to either the nervous system (muscles) or the endocrine system (hormones), what are they referred to as?
sensors
target
Communication System
Control Center
This responds to messages from the communication system and changes its level of activity to help you maintain homeostasis?
sensors
target organ or muscle
communication system
brain
Osmoregulation means....
maintain water levels
maintain temperature
maintain heart rate
maintain breathing
Thermoregulation means?
Maintain temperature
Maintain water levels
Maintain heart rate
Maintain breathing
When you are hot you....
sweat
shiver
get goosebumps
hairs stand up on arm
When you are cold you...
shiver to create heat
sweat
blood vessels dilate
increase heart rate
Positive Feedback loops are...
Counteract changes that move above or below set values.
more common
regulate body temp
Purposeful pushes above normal set values.
Negative Feedback loops are...
Purposeful pushes above normal set values.
Counteract a change to bring it back to normal set values
Are rare
Help with childbirth
Why does a nerve cell look different from a circular red blood cell?
There is no connection between shape and function
Cells all look exactly the same
Cells are shaped differently according to their function. A nerve cell needs long arms for communication.
All cells have the same exact job
Maintaining internal stable conditions is the definition of...
Hypertonic
Hypotonic
Homeostasis
Heterotroph
After the excited electrons are captured by the primary electron acceptor, water is split in a process known as what?
photosynthesis
photolysis
chemiosmosis
electron transport chain
As the excited electrons lose energy along the electron transport chain, they are fueling the process of:
Light capturing event
Chemiosmosis
Photolysis
What are the products of the light-dependent reaction?
Glucose
ATP and NADPH
Water and Oxygen
Plants produce oxygen when they photosynthesize. Where does the oxygen come from?
splitting water molecules
ATP synthesis
the electron transport chain
chlorophyll
The thylakoid membrane becomes damaged, causing the inside of the thylakoid to mix with the stroma.
Which of the following processes is likely to be most affected by this damage?
The reduction of NADP+ to NADPH
Sunlight absorption by the chloroplasts
The movement of electrons from photosystem II (PSII) to photosystem I (PSI)
ATP synthesis
What role do electrons play in the formation of NADPH?
Electrons from PS I cause the reduction of NADPH to NADP+
Electrons from PSII cause the reduction of NADP+ to NADPH.
Electrons from PS I cause the reduction of NADP+ to NADPH.
Electrons are gained causing the oxidation of NADP+NADP+.
A scientist suspects that a particular plant contains chloroplasts that lack photosystem II (PSII), even though it is able to live.
How could the scientist determine if PSII is missing from the plant's chloroplasts?
Test for the presence of sugar
Test for the presence of oxygen in light
Test for thylakoid presence in the chloroplasts
Match the reaction center in PSI & PSII with its name.
PSI is named P700
PSI is named P680
PSII is named P700
PSII is named P680
Where does photoactivation of electrons take place
Photosystems I and II
Photosystem I only
Photosystem II only
Electron Transfer Chain
Cyclic photophosphorylation differs from non-cyclic photophosphorylation in that _____________ is not made from the process.
ATP
G3P
NADH
NADPH
What is produced by the photolysis of two water molecules?
O2 + 4H+ + 4e-
O2 + 4H+ + 2e-
1/2 O2 + 2H+ + 2e-
1/2 O2 + 2H+ + 4e-
5 carbon sugar that combines with CO2 in the Calvin Cycle
3-PGA
G3P
RuBP
Glucose
Main products of the Calvin Cycle
Oxygen, NADP+, ADP
Glucose, CO2, ADP
ADP, NADP+, Glucose
ATP, NADPH, Oxygen
