GCSE biology paper 1 flashcards-topic 2

what is an enzyme

A biological catalyst (protein) that speeds up chemical reactions by lowering activation energy.

what is the lock and key model

when the substrate perfectly fits into the enzymes active site

what is the induced fit model

the enzymes active site changes shape slightly to fit the substrate more closely

explain why enzymes activity increases then decreases with temperature

more kinetic energy which means more collisions and it peaks at the optimum temperature after this, the enzyme denatures and the active site changes which makes the rate decrease 

practical-describe how to test for starch using iodine +interpret a positive result

add iodine if its blue/black then starch is present

if it remains orange then there is no starch

control variable-distilled water

which enzyme breaks down starch and where

amylase to starch to maltose. They are produced in salivary glands, pancreas and the small intestine.

practical-describe a method to investigate enzyme action (amylase and starch)

• use iodine drops in spotting tile

• sample mixture every 30s 

• record time until iodine stays orange 

• control variables-temperature, PH, concentration (of iodine)

which enzyme breaks down protein and where

protease to proteins to amino acids .They are produced in the stomach, pancreas and the small intestine

which enzyme breaks down lipids (fats) and where

lipase to lipids to glycerol + fatty acids produced in pancreas and small intestine

what is the role of bile

neutralises stomach acid, emulsifies to increase surface area for lipase action

what type of blood system do humans have

Double circulatory (heart to lungs to heart to body)

name the main blood vessels entering and leaving the heart

vena cava to right atrium

pulmony artery to lungs

pulmonary vein to left atrium

aorta to body

explain why the left ventricle has thicker walls than the right

it pumps blood at higher pressure around the body and needs stronger walls to keep it from exploding. (systemic circulation)

how are arteries adapted

thick, muscular ,elastic walls, small lumen to withstand high pressure

how are veins adapted

thinner walls , large lumen, valves for low pressure and prevention of backflow

how are cappillaries adapted

walls are one cell thick , large surface area for a short diffusion pathway

what is the function of white blood cells

defend against infection (antibodies , antitoxins)

what is the function of red blood cells

• no nucleus

• carry oxygen using haemoglobin which binds oxygen in lungs and releases in tissues

what is the function of platelets

blood clotting, seals wounds and starts the healing process

what is plasma and what does it transport

liquid part of blood and it carries CO2, urea, hormones, glucose, amino acids.

what is coronary heart disease

fatty deposits build up in coronary arteries which restricts blood flow and less oxygen gets to the heart 

restricted blood flow:

• causes chest pain

• shortness of breath

• possible heart attack (if artery is blocked)

how can coronary heart disease be treated

stents-widen the arteries

statins + heart transplant-lower cholestrol

heart bypass-blood rerouted

diet/exercise changes

what is cancer

uncontrolled cell growth and cells division

it happens due to mutations in the DNA of cells

whats the difference between benign and malignant humans

benign

• non-cancerous

• grows slowly + in one place

• doesnt spread

• less dangerous (than malignant)

malignant

• cancerous

• grows more quickly  and uncontrollably

• invades/damages surrounding tissues

• can spread to other parts of body

• requires urgent treatment as its life threatening

name the tissues in a leaf and their functions

palisade=photosynthesis

spongy mesophyll=gas exchange

xylem=water transport

phloem=sugar transport

guard cells=control the stomata

explain how water moves from roots to leaves

osmosis into the root hair cells then the xylem creates a transpiration pull from leaves and a continuous column of water is produced

practical-how to estimate transpiration rate with a potometer

measure distance of air bubble moves in cappillary tube over time

control variables-light , temperature, humidity and wind speed

why does transpiration rate increase with temperature or wind

more evaporation and diffusion which mean a steeper concentration gradient and faster water loss