biology topic 2- organisation

cells

building blocks that make up all living organisms

specialised cells

carry out particular functions

differentiation

process by which cells become specialised for a particular job

tissue

group of similar cells working together to carry out a specific function

organ

group of different tissues working together to perform a certain function

organ system

a group of organs working together to perform a particular function

organisms

organ systems working together

enzymes

• living things produce enzymes that act as biological catalysts

• made of proteins

• each has an active site with a unique shape that fits onto the substance involved in a reaction

• they’re specific to different substrates

• the enzyme and substrate bind to each other and the enzyme reacts releasing the products of the reaction

denature

• when an enzyme denatures, the shape of its active site changes and no longer fits the substrate.

• it needs a high temp but if it gets too hot then the bonds holding the enzyme together break

• optimum temp is around 37 degrees celcius

• pH affects enzymes similarly

• optimum temp is often neutral 7, but not in all cases e.g pepsin that breaks down proteins in stomach best works @ pH 2

practical to investigate effect on pH of enzyme activity method

1. drop of iodine in every well of spotting tile

2. bunsen burner on heatproof mat and tripod + gauze over bunsen burner. beaker of water on tripod and heat until 35°C, keep temp constant throughout

3. syringe- 1cm³ amylase solution and 1cm³ buffer solution with pH 5 to boiling tube, boiling tube in beaker wait 5 mins

4. different syringe- 5cm³ of starch solution to boiling tube

5. mix contents and start stop clock

6. continuous sampling- how long taken for amylase to break down all starch

   use pipette to take fresh sample every 30 seconds drop into well

   iodine browny orange- starch not present

7. repeat experiment with buffer solutions of different pHs

enzymes in digestion

• amylase

• protease

• lipase

amylase

• carbohydrase which breaks down starch into glucose

• made in 3 places; salivary glands, pancreas, small intestine

protease

• breaks down proteins into amino acids

• made in 3 places; stomach, pancreas, small intestine

lipase

• convert lipids into glycerol and fatty acids

• made in 2 places, the pancreas and the small intestine

bile

• produced in liver

• stored in gall bladder before released into small intestine

• alkaline so neutralises HCl so enzymes can work there

• emulsifies fat- makes into tiny droplets so bigger surface area so digestion is faster

role of salivary gland in digestion

produce amylase enzyme in saliva

role of liver in digestion

bile produced which neutralises stomach acid and emulsifies fat

role of stomach in digestion

• pummels food with muscular wals

• produces protease enzyme pepsin

• produces HCl to kill bacteria and give protease right pH to work at (2)

role of gall bladder in digestion

stores bile before released into small intestine

role of pancreas in digestion

produces protease, amylase, lipase and releases into small intestine

role of large intestine in digestion

excess water absorbed from food

role of small intestine in digestion

produces protease lipase amylase to complete digestion

digested food absorbed out of digestive system into blood

role of rectum in digestion

faeces stored

Benedict’s test

• test for sugars

• 5cm³ food sample to test tube

• 5 mins water bath 75° C

• 10 drops benedicts

• blue to green, yellow or brick-red

iodine solution

• test for starch

• 5cm³ food sample to test tube

• few drops iodine

• orange to blue or black

biuret test

• test for proteins

• 2cm³ food sample in test tube

• 2cm³ bieuret + mix

• blue to pink/purple

sudan III

• test for lipids

• 5cm³ food sample to test tube

• same amount water

• 3 drops sudan III + gently shake

• if present 2 layers, top brick red

ethanol

• 2nd test for lipids

• clear to emulsified/ cloudy

alveoli

air sacs that carry out gas exchange

surrounded by network of blood capillaries

blood to alveoli= lots of CO₂ little O₂

O₂ diffuses out of alveolus into blood (binds to hemoglobin to be transported)

CO₂ diffuses out of blood into alveolus to be breathed out

blood to cells- O₂ released from red blood cells and diffuses into body cells. CO₂ diffuses out of body cells into blood

respiratory system pathway

nose → trachea → bronchi → bronchioles → alveoli → bronchi → bronchioles → trachea → nose

double circulatory system

heart, blood vessels, blood

double because the right ventricle pumps deoxygenated blood to lungs and left ventricle pumps oxygenated blood around body

valves

prevents backflow of blood

4 chambers names

right atrium, right ventricle, left atrium, left ventricle

blood flow

1. blood into 2 atria from vena cava and pulonary vein

2. atria contract pushing blood to ventricles

3. ventricles contract forcing blood to pulmonary vein + aorta out of heart

4. blood flows to organs through arteries and returns through veins

5. atria fill and cycle starts over

blood flow (diagram?)

right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta → body

heart pacemaker

• resting heart rate controlled by group of cells in right atrium wall

• that produce small electric impulses

• that spread to surrounding muscle cells causing them to contract

arteries

• carry blood AWAY from heart

• heart pumps blood out @ high pressure so artery walls are STRONG and ELASTIC

• thick walls small lumen

• layers of muscles so strong

• elastic fibres so stretch/ spring back

capillaries

• involved in exchange of materials at tissues

• tiny

• thin wall 1 cell thick to increase rate of diffusion

• small lumen

• permeable walls

• supply food and O₂ take away waste like CO₂

veins

• carry blood TO the heart

• low pressure blood so walls not as thick as arteries

• big lumen to help blood flow

• valves so blood flows in correct direction

red blood cells

• carry oxygen from lungs to cells all over body

• bioconcave disc- large surface area to absorb oxygen

• no nucleus- more room to carry oxygen

• red pigment- haemoglobin

• lungs- haemoglobin binds to oxygen to become oxyhaemoglobin

• body tissues- oxyhaemoglobin splits into haemoglobin and oxygen to release oxygen to cells

white blood cells

defend against infection (more in topic 3)

platelets

• small fragments of cells no nucleus

• help blood clot

• stop microorganisms getting in

plasma

light yellow

carries:

• red blood cells

• white blood cells

• platelets

• nutrients- glucose/ amino acids

• CO₂ from organs to lungs

• urea from liver to kidneys

• hormones

• proteins

• antbodies + antitoxins from WBCs

stents

• keep arteries open

• for ppl who have coronary heart disease

• layers of fatty material build up causing coronary artists to be blocked and can't supply blood to muscles of heart

• lack of oxygen

• heart attack

• stents are tubes placed in arteries to keep it open and blood passing through

• keeps heart beating

stents pros

• lowers risk of heart attack for those with coronary heart disease

• effective for long time

• recovery time from surgery is relatively quick

stents cons

• risk of complications during surgery (e.g. heart attack)

• risk of infection from heart attack

• risk of patients developing blood clot near stent- thrombosis

communicable diseases

• reduce cholesterol in blood

• cholestrol- essential lipid body needs can cause health problems if too much of a certain bad one

• fatty deposits in arteries- coronary heart disease

• drugs to reduce amount of bad cholesterol present in bloodstrean and slows down rate of fatty deposits forming

stents pros

• reduce risk of strokes, coronary heart disease and heart attacks

• increase amount of beneficial cholesterol in blood that can remove bad

• prevent other diseases?

stents cons

• long term drug taken regularly- risk someone forgets to

• cause negative side effects- headaches, kidney failure, liver damage, memory loss

• effect not instant, takes time to kick in

communicable diseases

spread from person to person between animals and people. causes by bacteria/ viruses/ parasites/ fungi

non-communicable diseases

cannot be spread between people or between animals and people. last long time, get worse slowly

non-communicable diseases examples

• heart disease

• stroke

• cancer

• diabetes

• chronic lung disease

some factors that affect health

good balanced diet

stress

life situation- access to medicines/ healthy food/ condoms

risk factors for disease

exercise

air pollution

substances in body

risk factors interacting

lifestyle factors- developing or developed country- afford good healthy food etc

smoking

obesity

alcohol abuse

exposure to substances or radiation/ any carcinogens

cancer

uncontrolled growth and division of cells forming a tumour

benign

tumour grows until there's no more room. stays in one place. doesn't invade tissues in body. not dangerous not cancerous

malignant

tumour grows and spreads to neighbouring healthy tissues. cells can break off to other parts of body by travelling in bloodstream. form secondary tumours. dangerous. fatal. cancers.

risk factors for cancer

smoking

obesity

UV exposure

viral infection

inheriting faulty genes

epidermal tissue

covers whole plant

palisade mesophyll tissue

where most photosynthesis happens

spongy mesophyll tissue

contains air spaces to allow for diffusion of gases

meristem tissue

found @ growing tips of shoots and roots able to differentiate into lots of different types of cells to allow plant growth

leaf organisation

1. epidermal tissues covered with waxy cuticle which helps reduce water oss by evaporation

2. upper epidermis transparent so light passes through to palisade layer

3. palisade layer lots of chloroplasts for photosynthesis so near top to get as much sunglight

4. xylem and phloem form network of vascular bundle to deliver water+ nutrients to leaf and take away glucose produced from photosynthesis, support structure too

5. tissues of leaves adapted for gas exchange- lower epidermis with stomata to let in CO₂, opening and closing of cell controlled by guard cells, air spaces in spongy mesophyll increase rate of diffusion of gases

phloem

• transport food substances (mainly dissolved sugars) made in leaves to rest of plant for immediate use or storage

• columns of elongated living cells wit small pores in end walls to allow cell sap to flow

• transports in both directions

• translocation

xylem

• dead cells joined end to end with no end walls between and a hole down middle

• strengthened with lignin

• carry water and mineral ions from roots to stem and leaves

• movement of water from roots through xylem out leaves called transpiration stream

transpiration

• loss of water from plant

• caused by evaporation + diffusion of water from plant’s surface

• most happens @ leaves

• causes shortage of water in leaf

• more water up xylem to replace

• more water from roots

• constant transpiration stream

• side-effect of leaves adaptation for photosynthesis (stomata for gas exchange)

• higher water conc inside plant than air outside so diffuses out

factors affecting transpiration

• light- bright light greater transpiration rate

• temp- warmer = faster

• air flow- better air flow, greater rate

• humidity- drier air = faster transpiration

transpiration practical

guard cells

• kidney shape opening/ closing stomata

• lots of water in plant- guard cells fill and become plump and turgid so stomata opens and gas exchanges for photosynthesis

• shortage of water in plant- guard cells lose water becoming flaccid making stomata close to stop water vapour escaping

• thin outer walls

• thickened inner walls

• sensitive to light, closing at night

• adapted for gas exchange and controlling water loss in leaf