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A-level Biology Cells Exam

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more memory cells more antibodies produced It will be many years before it can be shown that this vaccination programme has reduced cases of cervical cancer (lines 7 to 9). Suggest two reasons why. - answer-Cancer takes years to develop Will be years before girls are sexually active Suggest one reason why vaccinating a large number of people would significantly reduce the spread of HPV through the population (lines 14 to 16). - answer-Virus not carried in vaccinated people and Non-vaccinated people more likely to contact vaccinated people Explain why these antibodies are referred to as monoclonal - answer-(Antibodies) produced from the same B cell The adults in group C produced the greatest increase in the number of memory T cells. Suggest what this shows about the BCG and MVA85A vaccines - answer-Contain the same antigens The reduced elasticity of the lungs (lines 6-7) causes breathing difficulty. Explain how. - answer-Lungs will not inflate and breathing will no longer be passive and will require force (energy) Apart from reduced elasticity, explain how changes to the lung tissue reduce the efficiency of gas exchange. - answer-Walls thicken and diffusion pathway increases The scarred and fibrous tissues reduce the surface area. Describe how B-lymphocytes respond when they are stimulated by antigens - answer-Divide by mitosis to produce clones that produce plasma cells. These make antibodies and memory cells. What is vaccination? - answer-injection of a weakened form of a pathogen to produce immunity (memory cells) Suggest one reason to explain the change in the percentage of people aged 65 and over being vaccinated. - answer-Better health education A student suggested that some people aged 65 and over were being vaccinated every year. Explain how the information in the bar chart supports this suggestion. - answer-Over half were vaccinated every year after 2000 An influenza virus consists of a protein coat surrounding nucleic acid. The influenza vaccine consists only of the protein coat of the virus. Explain how the influenza vaccine produces immunity in the body. - answer-Protein coat carries antigens that stimulates B cells to produce antibodies Although this vaccine is made from antigens from malarial parasites, it does not cause malaria. Explain why this vaccine does not cause malaria. - answer-Antigens are part of parasite - don't directly cause disease The blood from those taking part in the trial was also examined under the microscope at the beginning of the trial. Explain how this would enable those who had malaria to be identified. - answer-Parasites in red blood cells can be seen Give two factors, other than cost, that should be considered when selecting an antibiotic to treat a bacterial disease. - answer-Side effects How much bacterial resistance has built up Explain how each of these antibiotics slows down the rate of growth of bacteria. Tetracycline - Prevents tRNA binding - answer-Prevents binding to ribosomes - prevents protein synthesis - amino acids are not transported Explain how each of these antibiotics slows down the rate of growth of bacteria. Chloramphenicol - prevents peptide bond formation - answer-Prevents primary structure forming - proteins and enzymes can't be formed. Suggest why tetracycline has no effect on human cells. - answer-Animal cell (human) ribosomes are larger The MV + MMR group had more measles antibodies in their blood before vaccination than the MMR only group. Suggest an explanation for this. - answer-Maternal antibodies The medical officer used a statistical test to assess the effectiveness of the five different vaccines. (i) What would be the null hypothesis? - answer-there is no difference in the proportion / number of influenza cases between the 5 vaccines The MMR vaccine contains attenuated microorganisms. What is an attenuated microorganism? - answer-An alive microorganism that doesn't cause disease A child was given the MMR vaccine and was given a second dose of the vaccine as a booster later.

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A-level Biology Cells Exam
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Name the main biological molecule in:
The Cell Membrane
The Cell Wall - answer--Phospholipids
-Murein

Has stacked membranes arranged in parallel and contains DNA. - answer-Chloroplasts

Is an organelle and is not surrounded by two membranes. - answer-Golgi Apparatus

Human breast milk is produced and secreted by gland cells. These gland cells have adaptations
that include many mitochondria and many Golgi vesicles. The milk contains a high
concentration of protein.

Explain the role of these cell adaptations in the production and secretion of breast milk. -
answer-Mitochondria release energy in the form of ATP for vesicle transportation.
Golgi Vesicles transport the protein out of the cell.

Explain the advantages of lipid droplet and micelle formation. - answer-The droplets have a
large surface area which increases the rate of hydrolysis.
The micelles are smaller so are able to pass through the membrane carrying the products.

Suggest how the Golgi apparatus is involved in the absorption of lipids. - answer-It modifies and
processes triglycerides and combines them with proteins, forms vesicles and releases them via
exocytosis.

In cell fractionation, why is the solution ice cold? - answer-Stops enzyme activity to prevent
digestion of organelles

Is RNA in a Virus or Bacterium? - answer-Both

Is a cell wall in a Virus or Bacterium? - answer-Bacterium

Are enzyme molecules in a Virus or Bacterium? - answer-Both

Is a capsid in a Virus or Bacterium? - answer-Virus

Which cell membrane, cell wall and nucleus is a is white blood cell present in? - answer-Cell
surface membrane and nucleus

Which of the cell membrane, cell wall and nucleus is a bacterial cell present in? - answer-Cell
wall and cell surface membrane

,Some scientists support the theory that mitochondria are organelles that evolved from
prokaryotic cells.

(i) Give one piece of evidence that supports the theory that mitochondria evolved from
prokaryotic cells. - answer-Prokaryotic cells have circular DNA

What is the advantage to cells of having mitochondria? - answer-The respire aerobically so
provides energy in the form of ATP.

Describe how temporary mounts are made. - answer-Thin slice/section;

Stain with iodine

Add cover slip;

Describe how the scientist could have used the temporary mounts of leaves to determine the
mean number of chloroplasts in mesophyll cells of a leaf. - answer-1. Take a large number of
cells

2. Count number of chloroplasts;

3. Divide number of chloroplasts by number of cells

In which organelle does protein synthesis take place? - answer-The RER

Describe how the RER is involved in the production of enzymes. - answer-Its covered in
ribosomes which join amino acids together to make proteins in protein synthesis.

Describe how the Golgi apparatus is involved in the secretion of enzymes. - answer-It modifies
and packages into vesicles for transport.

Give two structures a bacterial cell may have that a white blood cell does not have. - answer-
Flagella and capsule

People given whole-cell vaccines were more likely to develop harmful side effects than the
people given the vaccines containing parts of the bacterial cells (lines 4-6).

Suggest reasons why. - answer-Heating was supposed to kill bacteria
so active bacteria are still alive meaning they can reproduce and make toxins.

People given whole-cell vaccines produced a greater range of antibodies against the bacterium
than the people given the vaccines containing parts of the bacterial cells (lines 7-8).

, Explain why. - answer-More bacteria = antigens;
and each antigen causes its own immune response.

Microfold cells take up the antigens and transport them to cells of the immune system (lines 6-
7). Antigens are not able to pass through the cell-surface membranes of other epithelial cells.
Suggest two reasons why. - answer-Not lipid soluble
Too large

Scientists believe that it may be possible to develop vaccines that make use of microfold cells
(lines 9-10). Explain how this sort of vaccine would lead to a person developing immunity to a
pathogen. - answer-Vaccine contains antigen
T-cells activate B-cells;
B-cells divide and forms clones
Plasma cells produce antibodies;
Memory cells produced meaning more antibodies remain in system

This photograph was taken using a transmission electron microscope. The structure of the
organelles visible in the photograph could not have been seen using an optical(light)
microscope. Explain why. - answer-Has low resolution as short wavelength

Use information in the diagram to explain why vancomycin does not affect human cells. -
answer-They don't have a cell wall

Chlamydomonas has adaptations that help it to maintain a high rate of photosynthesis.

Use information in the diagram to explain what these adaptations are. - answer-Light sensitive
eyespot
Flagellum for movement
Chloroplasts for absorption

Name two structures present in an epithelial cell from the small intestine that are not present in
a cholera bacterium. - answer-Nucleus
Lysosomes

Give one advantage of using a TEM rather than a SEM. - answer-Higher resolution

Give one advantage of using a SEM rather than a TEM. - answer-3D Image

Place the appropriate letters in the correct order to show the passage of an amino acid from the
cytoplasm at F until it is secreted from the cell as a protein at K. - answer-HJE

Use the information in the figure to explain a way in which fatty acids are important in the
formation of new cells. - answer-Fatty acids respired to release energy;
More triglycerides more energy released;

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