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What's a risk factor?
Something that increases chance.
What else do chloroplasts do?
Produce carbohydrates, sugars, lipids and proteins.
Why do some cells have 8.4 units of DNA and others 4.2?
8.4 has replicated DNA.
4.2 DNA hasn't replicated.
Define antigen.
Protein on surface pathogen which initiates an immune response.
Pros and cons of vaccines.
Prevent disease and cheaper than treating disease.
But costly.
What do light sensitive eye spots do in plant cells?
Detect light.
Why is an inhibitant of DNA polymerase effective against cancer?
Slows down DNA replication and mitosis so new strand isn't formed.
Why are other drugs used if one doesn't work?
It's resistant so there's less competition.
Describe induced fit model of enzyme.
The active site of an enzyme isn't complementary so changes shape to form enzyme - substrate complex.
How many ester bonds do triglycerides form?
What substance is found in both animal cells and plant cell?
Deoxyribose and DNA helicase.
Why are hydrogen bonds important in cellulose molecules?
They form microfibrils which provide strength.
Why is a spiral shape important in starch?
How can you prevent bacteria spreading in hospitals?
Screening doctors and washing hands.
2 ways which which a double blind trial improves reliability.
Prevents bias and placebo effect.
Why is it important that the epidermis is thin for plants?
Single layer of cells allow light to pass through.
Function of lysozyme.
Destroy indigested bacteria by hydrolysis of the cell wall.
Describe how you would test a piece of food for lipids.
Dissolve in ethanol alcohol then add water. A white emulsion shows the presence of lipids.
Suggest 1 advantage of the different percentage of cholesterol in red blood cells.
Red blood cells are free in the blood so cholesterol helps to maintain shape.
Explain why HSV viruses only infects nerve cells.
Viruses have antigens which are complementary to receptors in cell membranes which are only found on nerve cell membranes.
Advantage of programmed cell death.
Prevents virus replication.
Explain how Explain how microRNA allows HSV to remain in the body for years.
It binds by specific base pairing so prevents mRNA being read by ribosomes so prevents production of proteins that cause cell death.
What does bile - activated lipase do?
Increase growth rate.
Difference between starch and cellulose.
Position of hydrogen and hydroxyl groups on carbon atom 1 is inverted in cellulose.
Explain how cellulose is adapted for its function in plants.
They have un branched, straight long chains liked together by hydrogen bonds forming fibrils and provide strength.
Why can nucleotides only be added in the 5' to 3' direction?
DNA polymerase is specific and only binds to the 5' end as the shapes of the 5' and 3' end are different.
Explain how the behaviour of chromosomes causes the changes between F and G.
Chromosomes replicate and homologous chromosomes separate then sister chromatids separate.
2 reasons why you can't find AIDS.
To diagnose you look for symptoms and the number of helper T cells.
Why will the solution remain yellow if not infected with HIV?
HIV antibody isn't present so second antibody isn't present.
Why does the baby testing positive not prove it's infected ?
Children recieve antibodies form mothers so solution will always test positive.
What is a controlled well used?
To show only enzyme causes colour change.

To show washing is effective.
Advantage of TEM?
High resolution to see internal structure of organelles.
How do you observe position of starch grain?
Add drop of water to slide and place a thin section on it. Add iodine in potassium iodide then lower cover lip with mounted needle.
Which sugar ia produced when chewing . Why?
Maltose because salivary amylase breaks down starch.
What do you add instead of cooked saliva and why?
Boiled saliva as everything is the same apart form salivary enzymes are denatured.
What's the effect of chewing on digestion?
Some starch is already digested when chewed so digestion is faster.
Why aren't cancer patients given given a placebo?
It's unethical to fail to treat cancer.
Why can MM tumours be destroyed by the immune system?
Faulty protein is recognised as a foreign protein which T cells bind to. T cell stimulate B cells releasing antibodies.
Why do arrows point opposite ways in enzyme action?
DNA has antiparallel strands and nucleotides are alligned differently.

Enzymes have active sites with specific shapes and only complementary substrate bind to it.
Define inhibitor.
Substance that directly or indirectly interferes with function of active site.
How do you distinguish between competitive and non competitive inhibitors?
Increase substrate concentration.
What does a nucleotide structure consist of?
Pentose sugar.
Phosphate group.
nitrogen - containing organic base.
What bond link a polynucleotides?
Phosphodiester bonds.
Test for protein.
Sodium hydroxide.
Copper (11) sulfate.
Blue to purple.
Function of RNA?
Transfers genetic information from DNA to ribosomes.
What are the 2 stages of cell division?
Nuclear division.
Define T cell.
Type of WBC involved in the immune system which kills pathogens directly or activates B cells.
Define vaccination.
The administering of a vaccine containing antigens to give immunity.
Define Polynucleotide.
2 polynucleotide strands coil together forming DNA double helix.
Primary imune response.
Immune response triggered when foreign antigen enters body for first time.
Single- celled organism with no nucleus or membrane bound organelles.
Plasma cell.
A type of B cell that produces antibodies.
In nucleus and makes ribosomes.
Cell division where parent cell divides products in 2 genetically identical daughter cells.
Change of base sequence of DNA.
Monoclonal antibody.
Antibody produced from single group of genetically Identical B cells.
The ability to respond quickly to an infection.
Humoral immune response.
Involves B cells, clonal cells and antibodies.
ATP structure .
3 phosphate groups.
What can the inorganic phosphate released be used for?
Phoaphorylate other compounds making them more reactive.
Why is ATP better than glucose?
Hydrolysis is a single step reaction and is unstable so easily broken down.
What catalysis ATP to ADP?
ATP hydrolase.
What catalysis ADP to ATP?
ATP synthase.
What bond strengthens water?
Uses of water.
Metabolic reactions. Hydrolysis /condensation.
High heat capacity. Buffers changes in temp.
Large latent heat of vaporisation. Cooling effect with little loss of water.
Strong cohesion between water molecules.
Where are phosphate ions used?
DNA and ATP.
Where are H+ ions used?
Where are sodium ions used?
Co-Transport of amino acids and glucose.
Where are iron ions used?
Oxygen transport in haemoglobin.
Define magnification.
How much bigger the image is.
Difference between optical and electron microscopes.
Optical uses light and electron uses electrons to form image.
What does buffer do?
Maintain pH.
What does isotonic do?
Solution and cell has equal concentration.
What does Ice-cold do?
Reduce enzyme activity.
What are fungal cell wall made from?
What are bacterial cell wall made from?
What does vacuole do?
Maintain pressure.
What is the name for the protein coat of a virus?
What do viruses have on their surface?
Attachment proteins.
What do prokaryotic cells have?
Slime capsule.
How are prokaryotic cells different to eukaryotic?
No membrane bound organelles.
No nucleus.
Smaller ribosomes.
Murein cell wall.
Importance of mitosis.
Growth. Repair. Asexual reproduction.
What kind of responses are physical barrier and phagocytosis?
What are the slow responses?
Cell mediated and humoral.
Why can the immune system and lymphocytes distinguish between cells?
Different proteins have different tertiary structures.
Why does it take Time for pathogen control?
Lymphocytes need to build up.
Where do B lymphocytes mature and which immunity?
Bone marrow. Humoral immunity.
Where do T lymphocytes mature and which immunity?
Thymus gland. Cell - mediated immunity.
Which cells can present antigens?
Virus invaded, cancer, transplanted cells.
Similarities of T and B cells.
Provide immunity.
Produced from stem cells.
Types of WBC.
Differences of T and B cells.
Maturity and immunity.
Define monoclonal antibody.
Each clone produces specific antibody .
Antibody structure.
4 polypeptide chains. 2 heavy 2 Light.
How do antibodies prepare antigens for destruction?
Agglutination and phagocytosis.
Define antibody.
A protein produced by B cells in response to the presence of a pathogen.
Active immunity.
Immune system makes its own antibodies.
Passive immunity.
Given antibodies from a different organism.
What does HIV kill?
Helper T cells.