IGCSE Biology (Co-ordinated Sciences Double Award 2024)

excretion

removal of the waste products of metabolism, toxic materials, and substances in excess of requirements

respiration

breakdown of glucose inside cells to give energy

all living things (mrs gren)

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition

animal cell differences

no cell wall, no chloroplasts, no vacuole, glycogen food storage

plant cell differences

cell wall, chloroplasts, vacuole, starch food storage

animal cell has

semi permeable cell membrane, cytoplasm, glycogen food store, nucleus

plant cell has

permeable cell wall (glucose fibre), nucleus, cytoplasm, vacuole filled with liquid, chloroplasts (only in green plants), cell membrane, starch grain food storage

animal and plant cells are _______ for the jobs they do

specialized

magnification

size of drawing (mm)/actual size

when you increase the size of something, the surface area

does not increase relative

the bigger an object becomes, the _______surface it has _______

less, relative to its volume

no matter the size of the solid, the substance will _______. That is why cells are _______, so that the _______that is diffusing into them can be _______.

diffuse at the same rate, so small, oxygen,evenly spread/distributed into the whole cell easily.

as you get a _______ organism/cell, diffusion is made _______

larger, harder/takes longer

cells and multicellular structures have _______ to increase _______ to maximize _______. For example, _______.

specialized structures, surface area, rate of diffusion. Fish gills, leaf is not thick.

osmosis

diffusion of water through a SEMI PERMEABLE MEMBRANE. Osmosis takes place from an area of low solute concentration to high solute concentration (high water potential --> low water potential)

water potential

The ability of the water to move. There is more water leaving high water potential areas.

the water will tend to move until

there are the same number of molecules on both sides.

hypotonic

lower solute concentration

hypertonic

higher solute concentration

isotonic

equal solute concentration

animal cell add to water (ex. red blood cell)

water moves in, cell swells and eventually bursts

animal cell add to strong sucrose solution (ex. red blood cell)

water moves out, cell shrinks, cell deflates, crinkles

plant cell add to water

water moves in, cell swells, cell turgid (full of water). cell will not burst as the cell wall is quite strong

plant cell add to strong sucrose solution

water moves out, vacuole + cytoplasm shrink, cytoplasm comes away from the cell wall. Cell is plasmolysed. Cell wall remains the same/

Plasmolysed plant cell

The cell has lost water and the cytoplasm has shrunk; the membrane has pulled away from the cell wall

when drawing a graph

pay attention to scale on the axis!!! Independent variable on the x axis, dependent variable on the y axis.

autotrophs

organisms that make/produce their own food (like plants)

heterotrophs

organisms that need to eat food (like humans)

fibre is found in

the cell wall

lipids are found in

cell membrane

fats vs oils

fats - found in animals, solid at room temp. oils - found in plants, liquid at room temp.

Monomers

small unit that can join together with other small units to form polymers (larger substances)

Carbohydrates are made of

monosaccharides

proteins are made of

amino acids

main food chemicals are

carbohydrates, proteins, lipids, minerals, vitamins, fibre, water

carbohydrates

provide energy

simple carbohydrates

eg. glucose - sweet and soluble, provide immediate energy

complex carbohydrates

polymers/polysaccharides made from simple sugars. Used as energy store - eg starch, glycogen.

Examples of simple carbohydrates

fruit, vegetables, sugars, milk

Examples of complex carbohydrates

whole wheat bread, pasta, rice, oats, potatoes

lipids

long term energy storage (2x as much as carbs). Used as insulators, used in cell membranes, water proofing (like waxy leaves)

examples of foods containing lipids

margarine, fried food (churros, chips, fries)

proteins

made of long chains of amino acids, used for bodybuilding and repair

there are _______ amino acids. _______ are essential and must be eaten. The rest can be _______.

20, 8, made by the body

examples of proteins

meat and beans

vitamins and minerals

needed in very small amounts, but are essential.

examples of minerals

iron, zinc, calcium, etc.

examples of vitamins

K, B, E, B12, etc.

malnourished

Having a diet that lacks the correct balance; too much or too little of one thing

turgor pressure

The pressure that water molecules exert against the cell wall

Chemical elements that make up carbohydrates, fats, and proteins

oxygen, carbon, hydrogen, (protein: nitrogen too)

starch and glycogen made of

glucose

fats and oils are made of

fatty acids and glycerol

test for starch

add iodine, positive test turns black

test for reducing sugar

add benedict's solution, boil, positive test turns dark orange

test for protein

add biuret solution, positive test turns purple

test for fats and oils

add equal parts ethanol and water, shake well, positive test turns cloudy/white

water is

important as a solvent

Enzymes are a type of ______ called ______ because they are made by ______. They are a type of ______.

catalyst, biological catalysts, living organisms, protein molecule.

substrate

(enzyme specific) something that reacts to make a product

The enzyme has a ______ so that a ______ can fit and carry out its reaction. Each enzyme is specific for one job and can only do ______.

specific shape, specific substrate, one thing

active site

The part of an enzyme where the chemical reaction occurs. Specific to the substrate it catalyses.

How does an enzyme reaction work?

The substrate fits into the active site of the enzyme. The enzyme causes chemical change in the substrate.

Why, up to a certain point, does increasing the temperature of an enzyme increase the rate of reaction?

the molecules and enzymes increase KE and move around more and faster meaning they are more likely to bump into each other

Why does too hot a temperature cause the rate of reaction to slow and eventually an enzyme to denature?

because it causes the active site to change in shape slightly so it takes longer for the substrate to fit. Eventually, the substrate no longer fits.

optimum temperature

The temperature at which an enzyme is most active

denatured enzyme

An enzyme which no longer functions

effect of cold temperatures on enzymes

Cold temperatures decrease the rate of reaction because molecules are moving slower and are less likely to collide, but cold temperatures do not denature the enzyme, so if the temperature is brought back up, the chemical reaction will speed back up to a normal process.

Effect of pH on enzyme activity

All enzymes work best at optimal pH. above and below the optimal pH the rate of reaction decreases. Extreme pH changes can denature the enzyme.

balanced diet

contains all the nutrients in the right amounts that the body needs (carbohydrates, protein, fats, vitamins + minerals, and fibre)

Vitamin C

from citrus, deficiency scurvy(gums bleed, swollen, tired), helps with repair of body tissue/immune system

Vitamin D

from sunlight/fish oil/red meat, deficiency rickets (leg bones weak and bent), helps with bones and teeth

Iron

from red meat/pulses (lentils, beans, etc.), deficiency anemia (not enough O2 - tired, dizzy) carries O2, needed for hemoglobin

Calcium

from dairy/bones of fish like sardines, deficiency bones and teeth go brittle, helps with bones and teeth

Malnutrition is caused by

unbalanced diet

Kwashiorkor

protein deficiency

Marasmus

lack of energy

digestion

breakdown of large insoluble molecules (eg. protein, starch) into small molecules (eg. glucose, simple sugars) which can be absorbed and moved around the body easily.

ingestion

taking in food

absorption

movement of digested food molecules through the walls of the small intestine and into the bloodstream.

assimilation

movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

egestion

passing out of food molecules that have not been digested as feces through the anus

Egestion vs excretion

excretion is things are chemically changed in the cells but egestion is just passing through (???)

digestion can be ______, eg. teeth, or ______, eg. enzymes

mechanical, chemical

What does saliva do?

Saliva contains the enzyme amylase which breaks down starch and simple sugars (maltose). It also helps food pass into the oesophagus.

What do teeth do?

Teeth break food down to increase surface area. THis makes it easier to swallow and the more surface area, the higher the enzyme activity.

What does the stomach do?

Stomach acid pH 2 helps the enzyme pepsin to break protein into amino acids (optimum pH). It also kills microbes (denatures enzymes).

How does food move down the esophagus?

peristalsis (wave of muscle contractions)

where is bile produced?

the liver

Where is bile stored?

gall bladder and released from the bile duct.

What does bile do?

emulsifies fat (breaks down into smaller droplets) to increase surface area and neutralises mixture of food and gastric juices entering duodenum to provide suitable pH for enzyme activity

What does the small intestine do?

(The small intestine releases amylase) Absorption of food chemicals takes place.

amylase breaks starch down into ______
Protease breaks down protein into ______
Lipase breaks down fats to ______

simple sugars (eg. maltose), amino acids, fatty acids and glycerol

Where do amino acids and glucose go after the small intestine?

blood capillaries

Where do fatty acids and glycerol go after the small intestine?

the lacteals

What are lacteals?

part of the lymph system and drain into the blood

What does the large intestine do?

absorbs water

incisor teeth

cut and bite chunks of food (4 on top, 4 on bottom)

canine teeth

for tearing. Very sharp, pierce food

premolars (bicuspids)

4 of them, for grinding and chewing