Topic 1

Seite 1

Q1)

Due to the dipole nature of water hydrogen bonds for between molecules. Hydrogen bonds are important in giving water its properties because:

hold molecules together so water is a liquid at room temperature.

h bonds create cohesion, which is important in the transport of water and dissolved substances in the xylem

means it takes a lot of energy to heat water up (high specific heat capacity) and also to turn into a gas (high latent heat vaporisation). Temperature fluctuations small in living things, sweating and transpiration take energy.

TRANSPORT AND CIRCULATION

Q2)

in water, the oxygen atom is slightly negative and the hydrogen atoms are slightly positive, because the oxygen atom is more electronegative.

Q3)

In very small organisms simple diffusion is fast enough but big organisms have a much smaller surface area to volume ratio, so there is not enough surface to serve the needs of the large volume inside by diffusion. Organisms in order of largest to smallest SA/V ratio:

Yeast

Daphnia

Goldfish

Golden retriever

Elephant

Killer Whale

CARDIAC CYCLE AND HEART RATE

Q1)

The chamber in the heart which pumps blood from the heart to the lungs is the right ventricle.

The chamber which receives blood from the vena cava is the right atrium.

The chamber which pumps blood from the heart to the aorta is the left ventricle.

Valves open and close due to pressure differences between one side and the other. (pressure gradients),

Elastic recoil of the heart muscles lowers pressure in the atria and pressure, drawing in blood.

Q2)

Daphnia are suitable for experiments about heart rate because:

they are abundant and easily obtained

they are transparent

they have a very simple nervous system

CARDIOVASCULAR DISEASE

Q1)

Factors which must be present for a blood clot to form:

fibrin

calcium ions

vitamin k

thrombin

thromboplastin

Q2)

Platelets are also needed for the clotting process.

Atherosclerosis

damage to the endothelial lining of artery

inflammatory response, white blood cells move into the artery wall

cholesterol builds up leading to the formation of an atheroma

build up of calcium salts and fibres leading to plaque formation

STRUCTURE AND FUNCTION OF CARBOHYDRATES

Q1)

They all have different monosaccharides.

lactose has glucose and galactose

maltose has glucose and glucose

sucrose has glucose and fructose

Monosaccharides

glucose -main substance for respiration, soluble, osmotic effect

galactose - soluble, osmotic effect

fructose - fruit sugar, soluble, osmotic effect

Disaccharides

lactose - milk sugar, soluble

maltose - malt sugar found in germinating seeds, soluble

sucrose - main transport sugar in plants, soluble

Polysaccharides

amylose - unbranched, alpha glucose, in spirals so compact, insoluble, no osmotic effect.

amylopectin - branched chains of alpha glucose, lots of terminal ends so digested more rapidly than amylose, insoluble, no osmotic effect.

glycogen - branched chains of glucose molecules, compact, insoluble, no osmotic effect.

STRUCTURE AND FUNCTION OF LIPIDS

Q1)

Ester bonds and glycosidic bonds are both formed from a condensation reaction and broken by hydrolysis.

Q2)

in the hydrolysis of a triglyceride molecule, a glycerol an 3 fatty acid molecules will be formed.

The difference in saturation of the fatty acids changes the structure, physical properties and biological significance of the triglyceride:

saturated (fats) - strong intermolecular forces, solid at room temp, straight chain molecule

monounsaturated (oils) - intermolecular forces weaker because of kinked shape, liquid at room temp, molecule with one kink in chain

polyunsaturated (oils) - intermolecular forces even weaker, liquid at room temp, molecule with several kinks in chain

transport and circulation

cardiac cycle and heart rate

cardiovascular disease

structure and function of carbohydrates

structure and function of lipids