biology: organisation

what is a tissue?

a group of similar cells that work together to carry out a particluar function

what is an organ?

a group of different tissues tissues that work together to perform a particule function

what is an organ system?

a group of organs working together to perform a particular function

what are enzymes?

biological catalysts

what is a catalyst?

substance that speeds up the rate of a chemical reaction without being changed or used up

what is an active site?

the region on the enzyme where the substrate binds

what is the induced fit model of an enzyme?

the substrate changes slightly to fit the shape of the active sight

what happens is an enzyme gets too hot?

• changes the shape of the active site

how do you calculate the rate of a reaction?

rate = 1000/time

what do carbohydrases do?

convert carbohydrates into simple sugars

where is amylase found?

• salivary glands

• pancreas

• small intestine

what does protease do?

breaks down proteins into amino acids

where is protease found?

• stomach

• pancreas

• small intestine

what do lipases do?

break down fats to fatty acid and glycerol

where is lipase found?

• pancreas

• small intestine

where is bile produced

stored and released?

what does bile do?

• neutralises stomach acids (enzymes work best in alkali conditions

• emulsifies fats (breaks down fats so they have a larger surface area for enzymes)

what is the function of the large intestine?

absorb excess water from food

what is the function of the hydrochloric acid in the stomach?

• kill bacteria

• provided the right pH for protease

what is the test for sugars?

• add benedict's solution to a food sample in a water bath

• solution turns brick red if sugar is present

what is the test for starch?

• add iodine

• turns blue/black if starch is present

what is the test for proteins?

biuret solution changed from blue to purpose if protein is present

what is the test for lipids?

• sudan iii solution

• if lipids are present

what are in your lungs?

• bronchi

• bronchioles

• alveoli

how do you calculate breathing rate?

breaths per minute = number of breaths / number of minutes

what is a double circulatory system?

• deoxygenated blood is pumped to lungs then taken to heart

• oxygenated blood pumped to body

• deoxygenated blood returns to heart to be pumped to lungs

where are pacemaker cells found?

right atrium

what is the function of arteries?

carry blood away from the heart

what is the function of capillaries?

site of exchange between blood and tissues

what is the function of veins?

carry blood to the heart

how are arteries adapted to their function?

• strong

how are capillaries adapted to their function?

• permeable walls for diffusion

• thin walls (one cell thick) to decrease diffusion distance

how are veins adapted to their function?

• bigger lumen to help blood flow

• have valves to keep blood flowing the right direction

what is the function of red blood cells?

carry and release oxygen into cells

how are red blood cells adapted to their function?

• on nucleus to allow for more room to carry oxygen

• biconcave shape provided a large surface area

what is the function of platelets?

blood clotting to stop bleeding out and microorganisms infecting wound

what is carried in plasma?

• blood cells

• CO2

• urea

• hormones

• proteins

• antibodies

what is coronary heart disease?

layers of fatty material build up inside the coronary arteries

what is the function and risk of stents?

• tubes inserted in arteries to keep them open so blood and flow

• risk of surgical complications and blood clotting near stent

what is the function of statins?

• reduce the amount of LDL cholesterol in bloodstream

• slows down the rate of fatty deposits forming

what are the disadvantages of statins?

• long term drug that need to be taken regularly (risk of forgetting)

• can have negative side effects (headaches

what is an artificial heart?

• a mechanical device that pumps blood for a person whose own heart has failed

• less likely to be rejected than transplant

what is health?

the state of physical and mental wellbeing

what factors can affect health?

• diet

• stress

• disease

what is a risk factor?

something that increases a person's chances of developing a non communicable disease

what is the financial cost of non communicable disease?

• cost of NHS research and treatment

• family member with disease may have to give up their job

which part of a leaf contains lots of chloroplasts?

palisade layer

where are stomata found?

lower epidermis

what is the function of a waxy cuticle on plants?

• protects leaves

• reduces water loss

why is the upper epidermis of a plant transparent?

so light can pass through to the palisade layer

what is transpiration?

• evaporation of water from plant leaves

• causes roots to draw up water (constant transpiration stream)

what is the function of a phloem tube?

• transport sugars from leaves to the rest of the plant (translocation)

• transport goes in both directions

• made of columns of living cells with small pores in end walls to allow cell sap to flow

what is the function of xylem cells?

• made of dead cells joined with no end walls

• carry water and mineral ions from the roots to the stem and leaves (transpiration)