Biology Unit 1

What are the features of a Globular protein? (5)

Round, Compact, Made up of multiple polypeptide chains,Hydrophilic chains are on the outside; hydrophobic chains face inwards, They're soluble and therefore easily transported in fluids.

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Describe Glycogen (7)

The main energy storage material in animals, 1-4 and 1-6 glycosidic bonds, Lots of side branches, Glucose can be released quickly (which is iportant for energy release in animals), Compact, Insoluble (doesn't affect osmotic balance), Large

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What is the role of tRNA in protein synthesis? (3)

tRNA attaches to /transports specific amino acids, tRNA binds to mRNA, two tRNA bring amino acids together for peptide bonds to be formed

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What is the role of mRNA in protein synthesis? (5)

mRNA is a copy of the DNA strand, mRNA codes for amino acid sequence, mRNA leaves the nucleus into the cytoplasm, It's used in translation, It binds to a ribosome

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How does Gene Therapy work? (5)

Normal/correct genes/alleles are used, Gene/allele/DNA introduced into cells, This is done using a Vector, Such as altered viruses/plasmids/liposomes, Repeated treatment is needed

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Describe endocytosis (2)

Used for bulk transport of substances into the cell, Vesicles are created from the cell surface membrane, bringing their contents into the cell

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Describe Germ Line therapy (3)

Involves changing the alleles in the sex cells, Every cell of any offspring will be affected by the gene therapy, It's illegal in humans

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Describe Somatic therapy (2)

Changing the body cells (particularly those most affected by the disorder), It doesn't affect the sex cells, so any offspring could still inherit the disease

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What are the social/ethical issues relating to genetic screening? (3)

Prenatal tests increase the risk of miscarriage by around 1%, False results could provide incorrect information, Some people consider it unethical to abort a foetus because it has a genetic disorder

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Describe amniocentesis (3)

Offered to women with a family history of a genetic disorder, Carried out 15-16 weeks into pregnancy, A sample of amniotic fluid is obtained using a fine needle and the DNA is analysed.

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Describe Chronic Villus Sampling (CVS) (3)

Carried out 8-10 weeks into pregnancy, A sample of cells is taken from the chronic villi using a fine needle, The DNA is analysed

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Describe active transport (3)

It's against a concentration gradient, Through carrier proteins that change shape, Requires energy (ATP)

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Describe Facilitated diffusion (4)

High to low concentration, Used by hydrophilic molecules or ions, Through channel proteins or via carrier proteins that change shape, Passive- no energy is required

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What is the role of a glycoprotein in the cell membrane? (3)

Cell signalling, Cell recognition, Binding cells together

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What is the role of the channel protein in the cell membrane?(1)

Used in facilitated diffusion

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What is the role of cholesterol in the cell membrane? (1)

To regulate membrane fluidity

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What is a disaccharide? Give an example. (3)

2 sugar units, Joined by a glycosidic bond, Sucrose/Lactose/Maltose

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What are the features of a good study? (4)

Clear aim,Representative sample, Valid/Reliable results, Suitable time scale

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Describe diffusion (4)

High to low concentration until an equilibrium is reached, Hydrophobic/small uncharged molecules, Through phospholipid bilayer, Passive- no energy required

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How does lowering blood cholesterol levels reduce the risk of CVD? (3)

There is less cholesterol in the blood to build up on artery wall, Less likely to develop atherosclerosis, Which can decrease the flow of blood to the heart muscle

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Describe the role and structure of starch (3)

Plants store excess glucose as starch, It's a mixture of two polysachharides of alpha glucose: amylose and amylopectin, Starch is insolublein water (and therefore doesn't affect the osmotic balance)

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Describe the structure of amylose (5)

Long, unbranched chain of glucose, 1-4 glycosidic bonds, Coiled, Compact, Good for storage because a lot of energy can be stored in a small space

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Describe the structure of the mammalian heart (6)

Four chambers, It has a separate left and right side, The atria are above the ventricles, It has muscular walls, Cardiac muscle is stronger/thicker on the left side, Atrioventricular valves separate the atria and ventricles

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What are the advantages of a closed circulatory system? (3)

Higher Pressure, Faster, More efficient

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Which end of the H2O molecule is positive?

The Hydrogen end

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What are the features of a fibrous protein? (4)

Made up of long and insoluble polypeptide chains, Chains are held together by many bonds (eg. disulfide&hydrogen), They're strong, Often found in supportive tissue

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Describe the process of Blood Clotting(4)

Thromboplastin is released from the damaged blood vessel, Prothrombin is converted into thrombin, Fibrinogen changes into fibrin, Fibrin fibres form a mesh to trap platelets

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What is an allele?(2)

One of the alternative forms of a gene, it determines which aspects of a particular characteristic an organism with display.

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What is a genotype?

The genetic composition of an organism, i.e. the combination of alleles it posesses

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What are the properties of arteries? (4)

Narrow lumen, Thicker walls, More collagen & elastic fibres &smooth muscle, No valves

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Describe Ventricular systole (3)

The ventricles contract from the base of the heart upwards; increasing pressure in the ventricles. This pushes the blood up and out through the arteries.The pressure of blood against the atrioventricular valves closes them to prevent further backflow

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Describe Diastole (4)

The atria&ventricles relax during diastole, Elastic recoil of the relaxing heart walls lowers pressure in the atria&ventricles, Blood is drawn back towards the ventricles, closing semilunar valves to prevent further backflow,

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What are the risk factors for CVD?

High BP, Obesity, High blood cholesterol, Smoking, Genetic inheritance, Age, Gender, Inactivity

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Describe exocytosis (2)

Used for bulk transport of substances out of the cell. Vesicles fuse with the cell surface membrane, releasing their contents.

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What happens in Atherosclerosis? (6)

Damage to the endothelial lining, Inflammatory response-white blood cells move into the area. Cholesterol builds up, forming an atheroma, Calcium salts and fibres build up leading to plaque formation, Narrowing of the artery, Raised Blood pressure

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What is a cohort study? (1)

A group of people are followed over time to see who develops the specified disease.

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Name an enzyme involved in DNA replication

Polymerase

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Name the two products formed from the breakdown of triglycerides (2)

Fatty acids, Glycerol

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What are the features of a gas exchange surface? (3)

Large surface area, numerous capillaries around alveoli, Thin walls of the alveoli and capillaries ( short distance between the alveolar air and the blood in the capillaries)

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What is a case-control study?(1)

A group of people who have a specific disease are compared with a group of people without the disease.

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What are the benefits of a double circulatory system?(2)

Blood can pass slowly through the region where gas exchange takes place (maximising the transfer of oxygen), Then be pumped vigorously around the rest of the body, enabling he organism to be very active

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Describe Amylopectin (4)

It's a long branched chain of glucose, It contains 1-4 and 1-6 glycosidic bonds, Side branches allow enzymes to get to the glycosidic bonds easily, Glucose can be released quickly

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What is a monosaccharide? Give an example. (2)

They are single sugar units: Glucose/Galactose/Fructose

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What bonds hold together the primary structure of a protein? (1)

Peptide bonds form between amino acids

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What bonds hold a protein's secondary structure together? (1)

Hydrogen Bonds

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What bonds hold together a protein's tertiary structure? (4)

Ionic interactions, Disulfide bonds, Hydrophobic/Hydrophilic interactions, Hydrogen bonds

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What is a polysaccharide? (2)

A chain of many saccharides, Held together by glycosidic bonds, eg Amylose/Amylopectin/Glycogen

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Describe how you would investigate how temperature affects membrane permeability (5)

Wash the beetroot thoroughly. Place each piece in a different water bath. Time spent in the water bath must be the same for each piece. A colorimeter should be used to test absorbance. There should be a range of at least 5 temps. Repeats are needed.

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Describe an experiment that could be used to compare caffeine content of drinks

Daphnia's heart rate should be determined before treatment. Then it should be placed into the drinks one by one and allowed to acclimatise. Using a microscope, the new heart rate should be taken. Temperature should be controlled. Reference to repeats

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Explain the importance of the primary structure of an enzyme to its function (4)

Primary structure determines 3D folding. The position of amino acids determine the position of bonds, The shape of the active site is determined by position of amino aids. The active site is specific to the substrate.

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How does CF affect the Respiratory system? (4)

The cilia are unable to move the mucus, Therefore mucus builds up in the airways. Some airways an become blocked by the mucus, reducing gas exchange and causing breathing difficulties. Sufferers are prone to lung infections.

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How does CF affect the Digestive system?

Mucus blocks the pancreatic duct, so digestive enzymes can't reach the small intestine, so food is not properly digested. The mucus can cause cysts to grow in the pancreas, inhibiting the production of enzymes.

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How does CF affect the reproductive system?

In women, mucus can block the cervix, preventing the entry of sperm.. In men, the sperm duct is either missing or blocked with mucus, so sperm cannot leave the testes.

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Explain why phospholipids form a bilayer (3)

The fatty acid tails are hydrophobic and in the middle of the bilayer. The phosphate heads are hydrophilic and face outwards. This is because the cytoplasm is polar in nature.

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What is meant by the term hydrophobic?

Insoluble in water / does not dissolve in water / non-polar

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Explain why the cell surface membrane is described as a fluid-mosaic (2)

(Fluid because) phospholipids move (around membrane) ; (Mosaic because) membrane contains proteins / glycoproteins (lying amongst phospholipids)

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Name the two monosaccharides produced from the hydrolysis of sucrose.

Glucose & Fructose

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State one function of triglycerides in living organisms

Energy store or source / insulation /waterproofing / production of metabolic water / buoyancy / protection

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State two factors which influence the rate of diffusion across a cell surface membrane. (2)

concentration gradient ; temperature ; (diffusion) distance / thickness (of membrane) ; permeability (of membrane) ; surface area (of membrane) ; size of, molecules / ions / particles ; polarity / solubility in lipids

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Describe what is meant by the semi-conservative replication of DNA. (4)

making new/opying DNA; makes identical copies; new molecule has one old and one new strand; DNA strands separate; each strand acts as a template;individual nucleotides line up against (old) strand ; complementary base pairing ; nucleotides joined

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Water has a high _______ _____ _________

Specific heat capacity

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Explain what is meant by the Tertiary structure of a protein (3)

Folding of secondary structure ; To form irregular / 3D / globular shape ; Maintained by, hydrogen / ionic / disulphide bonds / Bonding determined by R-groups ; Shape is important for function

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State one function of each of the following components of the cell surface membrane. a) Carbohydrate b) Protein (2)

Carbohydrate: Cell recognition / cell adhesion ; Protein: Transport of molecules OR receptor for hormone OR enzymes

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Explain why water molecules are described as dipolar (2)

Charge is not equally distributed throughout molecule / one part is positive and the other part is negative; Hydrogen (atoms) have (slight) positive charges; Oxygen (atom) has a (slight) negative charge

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One of the properties of water is that it has a high specific heat capacity. Explain why this property is important for organisms that live in water. (2)

Idea that a lot of {energy / heat} is needed to change temperature ; Temperature of their {environment / habitat} does not {fluctuate / change} much / reference to {thermostable / thermobuffer}; Reference to effect on metabolic {rate / reactions}

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Describe the process of translation. (5)

Occurs on ribosome;Two tRNA molecules (held in position in ribosome);Each carrying a specific amino acid;Reference to binding of tRNA to complementary bases on mRNA; Peptide bonds form between amino acids; Ribosome moves along mRNA;Until a stop codon

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Biology Unit 1

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