bio igcse

nucleus

controls activities of the cell

cytoplasm

• where chemical reactions accur

• contains organelles

chroroplast

• contains chlorophyll and essential enzymes to produce glucose by photosinthesis

cell wall

supports and protects the cell

cell membrane

controls movement of substances in and out of cell

vacuole

• contains cell sap

• presses out on the cell wall to mantain shape

ribosomes

synthesiste proteins

mitochondria

site of aerobic respiration to release energy

ciliated cells (specialised cells)

• function: movement of mucus in the trachea

• specialisation: layer of tiny hairs to move the mucus

root hair cells (specialised cells)

• function: absorption of water and ions in roots of plants

• specilisation: long extensions to increase surface area

xylem vessels (specialised cells)

• function: transport water and support the plant

• specialisation: no cytoplasm or end wall, water can move freely

nerve cells (specilised cells)

• function: conduction of nerve impulses - reflex

• specialisation: many branched endings to pass the signal quickly to many other nerve cells

red blood cells (specialised)

• function: transport of oxygen

• specialisation: no nucleus and biconcave, more room for heamoglobiin and oxygen

sperm cells (specialised)

• function: reproduction

• specialisation: tail for swimming, lots of mitochondria for energy

egg cells (specialised)

• function: reproduction

• specialisation: large size, energy stores and chemicals to prevent multiple sperm entering

equation for calculating magnificatioon

M= I ÷ A

A = I ÷ M

I = M X A

diffusion definition

the net movement of particles form a region of high concentration to a region of low concentration down a concentration gradient, as a result of their random movement

what causes particles to diffuse

kinetic energy of random movement of molecules and ions

how is diffusion important for organisms

• gas change in alevoli

• uptake od nutrients in digestion

active transport - definition

the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

2 examples of active transport

• ion uptake by root hairs

• glucose uptake in villi and kidney tuboles

affecting factors on the rate of movement - diffusion

• surface area - larger surface are increases the rate of diffusion

• temperature - rate increases as temperature inceases as molecules have more kinetic energy, they move faster and collide more often

• conc. gradient - mantaining a conc. gradient increases the rate

• distance - the rate is faster if there is less distance to travel

osmosis - definition

the diffusion of water through a partially permeable membrane

• the net movement of water molecules form a region of high concenrtration to lower concentration through a partially permeable membrane

importance of osmosis to plants

ensures water is always being drawn in the plant

test for starch - IODINE

• place food to be tested on spotting tile

• 2-3 drops of IODINE SOLUTION

• positive result for starch = from yellow to blue black

test for protein - BIURET SOLUTION

• place food to be tested in test tube

• 5-6 drops of BIURET solution

• positive result = from blue to purple

test for glucose - BENEDICT SOLUTION

• place food sample in boiling tube

• add equal amount of BENEDICTS solution

• plaice boiling tube in hot water bath

• positive result = from blue to red

test for lipids - ETHANOL

• cut and place food sample in test tube

• cover with ethanol

• add stopper and shake

• add distilled water to half fill the test tube

• shake again

• positive result = cloudy white emulsion forms

simple and complex carbs common factors

• used for energy

simple carbs

• soluble in water

• small

• eg. glucose

complex carbs

• insoluble

• large (made of many simple carbs joined together )

• eg. starch

balanced diet - deifintion

an adequate intake of the nutrients and energy needed to sustain the body and ensure health

components of a balanced diet

• carbs

• proteins

• fats

• vitamins

• minerals

• water

• fibre

dietary needs - age

• children have a greater energy requirement from adults becauswe they are still growing

• elderly people have lower energy and protein needs

dietary needs - gender

• females have a lower energy requirement than men due to a more stored fat in their body

dietary needs - pregnancy

• pregnant women need more calcium for the fetuses bones

• more iron to make more blood cells

• carbs for energy to move a heavier body

• more protein to provide amino acids to develop more tissues

dietary needs - brestfeeding

• calcium, fats, proteins needed for milk prodution

malnutrition - definition

having too much, too little or an imbalance of the nutrients essential to remain free of health issues

vitamin a

• source: milk, eggs

• fhnction: good eyesight

vitamin c

• source: organges

• function: repair of skin tissue

vitamin d

• source: seafood, nuts

• function: bone growth

calcium

source: milk

function: strong bones / teeth

iron

• source: meat, spinach

• function: healthy blood

water

• source: fruit, water

• function: part of all body processes

fibre

• source: fruit, vegetables

• function: moving food along the alimentary canal

deficiency diseses

1. rickets - lack of sunlight, soft bones, legs bow outwards

2. anemia / iron deficiency - lack of iron, tiredness, lack of energy

3. scurvy - lack of vit C, sore arms and legs, tooth loss

ingestion

taking in substances, into the body through the mouth

absorption

movement of small food molecules and ions through the wall of the intestine into the blood

egestion

passing out of food that has not been absorbed or digested, as feces, through the anus

cholera

• disease caused by badcteria transferred in contamined water / food

• causes diarrhea and dehydration

amylase - enzyme

• secreted from - salivary glands AND pancreas

• acts in - mouth & small intestine

protease - enzyme

secreted from: stomach & pancreas

acts in: stomach & small intestine

lipase - enzyme

• secreted from: pancreas

• acts in: small intestine

where bile is produced and stored

• produced: liver

• stored: gallbladder

2 roles of bile

• neutralisation: neutralises acidic mixture of food and gastric juices enterinf the duodenum from the stomach. Provides a suitable pH for the enzymes in the ileum

• emulsification: breaks down fat globules of fat into smaller ones, increases surface area to allow fats to be better digested by lipases

enzyme - definition

proteins that function as biological catalysts, speeding up reaction in cells

catalyst definition

a substance that increases the rate of a chemical reaction and is not changed by the reaction

why enzymes are important to living organisms

they increase the speed of reactions in cells like respiration / photosynthesis , necessaty to sustain life

enzyme substrate specificity - definition

the active site of an enxyme has a complementary shape to fit just one specific substrate to form one type of product

investigate the effect of ph on enzyme activity

1. Add 2ml of amylase to a test tube

2. Add 1ml of pH2 buffer solution and leave for 5 minutes

3. Add iodine to the wells of a spotting tile

4. After 5 minutes add 2ml of 1% starch solution to the enzyme and

start a stopwatch

5. Every 10 seconds pipette some of the solution and add a few drops to

one well of iodine

6. Record the time it takes for the iodine to remain orange (not change

to black). This shows when the starch has all been broken down by

the amylase

7. Repeat this two more times

8. Repeat using buffer solutions for pH4, pH6, pH 8 and pH10

small intestine function

a region for the absorption of digested food into the bloodstream

2 places wherew water is absorbed in the alimentary canal

• small intestine ( absorbs more water)

• colon of large intestine

how are villi adapted for their function

• thin lining: short distance for food molecules to diffuse

• large surface area: folded to increase the surface area on which diffusion occurs. Microvilli to increase the surface area further

role of capillaries in villi

• take absorbed food away quickly to manitain a concentration gradient to ensure more molecules diffuse across

• take absorbed food cells where they are assimilated

adaptations of alveoli

• spherical shape gives a large surface area for diffusion

• this surface reduces the distance of diffusion

• good blood supply mantains a concentration gradient

• moinst surface allows gases to dissolve increasing the rate of diffusion

practical to investigate the effect of excercise on breathing

• record number of breaths per minute at rest

• complete one minute of intense excercise

• record breathing rate right after excercise

• repeat two more times and take an average for 2 / 3 minutes of excercise

IV - minutes of excercise

DV - breathing rate

CVs - type of excercise, individual completing the excercise

effects of physical activity on the rate / depth of breathing

during physical activity the rate + depth of breathing increase

• physical activity increases amount of CO2 in the blood

• this is deteced by the brain which sends a signal to the brreathing system to increase the rate of breathing

• this increases the amount of CO2 that can be removed from the body

aerobic respiration - definition

• the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

aerobic respiration - equation

• glucose + oxygen ➡ carbon dioxide + water

• C6H12O6+6O2 ➡ 6CO2 + 6H2O

anaerobic respiration - definition

the chemical reactions in cell that break down nutrient molecules to release energy without using oxygen

anaerobic respiration - equation

anaerobic respiration in animals : glucose ➡ lactic acid

anaerobic respiration in yeast: glucose ➡ ethanol + carbon dioxide

symbol eq anaerobic respiration in yeast: C6H12O6 ➡ 2C2H5OH + 2CO2

oxygen debt

lactic acid builds up in muscles and blood after vigorous excercise, this requires oxygen to be broken down, the amount required is oxygen debt

removal of oxygen debt

Continued raised heart rate after exercise transports lactic acid from muscles to the

liver. Continued raised breathing rate provides oxygen for the aerobic respiration of

lactic acid in the liver, breaking it down to water and carbon dioxide

role of anaerobic respiration in yeast and bread making

1. yeast concumes glucose in the bread mix and secretes ethanol and carbon dioxide

2. carbon dioxide makes the dough rise

3. ethanol evaporates them the heat of the oven

circulatory system - definition

a system of blood vessels with a pump and valves to ensure one way blood flow

lymphatic system - what is it

circulatory system for tissue fluid and lumphocytes, separate to the one for blood

functions of the lymphatic system

• recycles tissue fluid by returning it to the vena cava near the heart

• contain stores of lympgoytes in the lymph nodes that help protect the body from infection

function of shunt vessel

• links an artery directly to a vein

• constriction or dialation regulates hear loss

function of arteriole

• subdivision of arteries that carry blood to capillaries

• can regilate blood pressuee

artery - structure, function, adaptations

• structure: narrow lumen, thick elastic and muscular walls

• function: carry blood at high pressure away from the heart

• adaptations: muscular and elastic walls to withstand high presssure

vein - structure, function, adaptations

• structure: wider lumen, less muscular or leastic walls, valves

• function: carry blood back to the heart

• adaptations: valves to prevent blood flowing backwards

capilllary - structure, function, adaptation

structure: very narrow, one cell thick

function: allow exchange of substances in blood with body’s cells

adaptation: thin to allow substances to pass easly to and from the blood

impartance of the septum - heart

prevents deoxygenated blood on the right side from mixing with oxygenated blood on the left side

thickness of muscle wall of left and right ventricles

left has more muscle as it has to pump blood around the whole body

thickness of muscle wall of ventricles and atria

ventricles have more muscle as theu pump blood at a higher pressure

how the heart functions

• atria and ventricles contract at the same time

• during relaxation semilinar and atrioventricular valves are shut to prevent backflow of blood

• blood flows into the atria from veins

• when atria contract the pressuse opens and the atrioventricular valves and blood moves into the ventricles

• ventricles contract opening semilunar valves allowing blood to leave in arteries

coronary heart disease

caused by a blockage of the coronary arteries that cupply the heart muscle cells with glucose and oxygen

if no glucose reaaches the hart cells no aerobic respiration accurs

without energy the heart cells die leading to heart attack

red blood cells - function

transport oxygen for respiration to the cells of the body

white blood cells

fight pathogens that cause disease

lymphocytes - produce antibodies (large central nucleus)

phagocytes - phagocytosis ( irregular shaped nucleus )

platelets - function

fragments of cells that cause the blood to clot

plasma - function

liquid to transport the other blood components

transports soluble nutrients, hormones, co2

how are red blood cells specialised

• contain heamoglobin ( protein that carries oxygen)

• biconcave shape to increase surface area

• no nucleus, more space fir oxygen

heamoglobin

protein that carries oxygen

role of blood clotting

prevents blood loss and entry of pathogens

blood clotting process

• platelets release a substance that converts the soluble plasma protein into the insoluble protein

• forming a mesh of fibres around the cut, which hardens forming a scab

• with time the skin heals and the scab falls off

pathogen

• a disease causing organism

• eg. hiv, influenza

transmissible disease

• a disease in which the pathogen can be passed from one host to another

• eg. aids, flu

direct ways a pathogen can be transmitted

• through blood from cuts in the skin

• unprotected sex

indirect ways a pathogen can be transmitted

• contaminated food

• droplets in the air

vaccination - definition

injections to enhance the bodys defence against pathogens

• can be injections of antibodies for a specific diease or weakened versions of the disease