IGCSE 0653

Respiration

The chemical reactions in cells that break down nutrient molecules and release energy

Excretion

Removal from organisms of toxic materials and substances in excess of requirements

Nutrition

Taking in of materials for energy, growth and development

Movement

An action by an organism causing a change of position or place

Sensitivity

The ability to detect and respond to changes in the environment

Reproduction

The processes that make more of the same kind of organism

Growth

A permanent increase in size

Cytoplasm

A clear, jelly-like substance.

Palisade mesophyll cells

Carries out photosynthesis

Difference between the structure of a plant cell with an animal cell

Cell wall

Structure support and protection for plant cells (only)

Ciliated cells

Movement of mucus in the trachea and bronchi

Cell membrane

A double-layered membrane that surrounds the cell.

Sperm and egg cells

Reproduction

Red blood cells

Transport of oxygen

Cells

Substance that living organisms are made of

Nucleus

A double membraned organelle containing the cell’s DNA. DNA regulates the cell’s activities, making the nucleus the ‘control centre’ of the cell.

Root hair cells

Absorption of minerals for plants

Chloroplast

Contains chlorophyll.

Chlorophyll

A green pigmented structure that converts light energy into chemical potential energy

Amino acids

Makes up proteins

Diffusion
 

The net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement.

Substances move into and out of cells by diffusion through the cell membrane.

Iodine solution

Test for starch

Water

Important as a solvent in tests

Glucose

Makes up starch and glycogen

Carbohydrates Chemicals

Carbon, Hydrogen and Oxygen

Biuret test

Test for protein

Osmosis
 

The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane.

Water moves in and out of cells by osmosis through the cell membrane.

Proteins Chemicals

Carbon, Hydrogen, Nitrogen and Oxygen

Effects on plant tissues of immersing them in solutions of different concentrations

When you immerse plant tissue in solutions of lower water potential water diffuses out of the cell by osmosis.

When you immerse plant tissue in a solution of equal water potential to their cell cytoplasm there is no change because of net balance.

When you immerse plant tissue in solutions of higher water potential than their cell cytoplasm, more water diffuses in through osmosis.

Fatty acids and glycerol

Make up fats and oils

Fats Chemicals

Carbon, Hydrogen and Oxygen

Benedict’s solution

Test for reducing sugars

Ethanol emulsion test

Test for fats and oils

Enzyme shape

An enzyme’s active site and its substrate are complementary in shape.

Denatured

When an enzyme’s active site loses its shape meaning it can no longer work.

Denaturation is a permanent change.

Substrate

A substance on which enzymes act. An enzyme will only work on one substrate - it is substrate specific.

Changes in temperature on enzyme activity

As temperature increases to the optimum, the kinetic energy of the enzyme and substrate increases, causing more collisions between the enzyme and substrate.

An increase in temperature beyond the optimum causes the enzyme’s active site to become denatured.

Enzymes

Proteins that function as biological catalysts

Effect of changes in pH on enzymes

Deviating from the optimum pH (too high or too low) causes the enzyme’s active site to become denatured and the active site loses its important shape.

Enzyme activity

Enzymes and substrates collide to form enzyme-substrate complexes.

The substrates are broken down (or in some cases built up).

The products are released.

The enzyme is free to act again.

Germination

The process of seeds developing into new plants

Sepals

Hard layer that protects the flower while it is a bud

Fertilisation

Occurs when a pollen nucleus fuses with a nucleus in an ovule

Nitrate Ions

Making Amino Acids (Proteins)

Pollen Grains in Wind Pollinated Flowers

Smooth and light to be easily carried by wind

Increased Light Intensity

Increased Rate of Photosynthesis until a certain point

Petals

Attract insects for pollination.

Petals in insect pollinated flowers

Colourful

Anthers in wind pollinated flowers

Hang loosely outside flower

Xylem

Transport water / minerals and Support

Stomata, Spongy Mesophyll cells and Guard cells

Gas Exchange

Phototropism

Growth of a plant shoot toward or away from light.

Effect of Warmth in Seed Germination

Increases growth rate and enzyme activity

Chlorophyll

Transfers light energy into chemical energy in molecules, for the synthesis of carbohydrates

Stamen

the male reproductive organ of a flower

Ovaries

Contain ovules. These develop into seeds when they are fertilised.

Agents of Pollination

Animals (Mostly Insects), The Wind, Water

Stigmas

A sticky surface that catches the pollen during pollination

Nitrate Ion Deficiencies

Slow growth, weak stem, yellow leaves

Auxin

Made in shoot tip and spreads through the plant from the shoot tip. Is unequally distributed in response to light and gravity and stimulates cell elongation.

carbon dioxide + water → glucose + oxygen

The word equation for photosynthesis

Root Hair Cells

Collect water and mineral nutrients from soil. The large surface area of root hairs increases the rate of the absorption of water.

Anthers in Insect pollinated plants

Firm, Inside Flower

Cuticle

The waxy, waterproof layer that covers the leaves and stems of most plants.

Ovule

A structure that contains an egg cell

Pollination

The transfer of pollen grains from the anther to the stigma

Magnesium Ions

Make Chlorophyll

Magnesium Ion Deficiencies

Yellowing of Leaves

Uses of starch

Respiration, Active transport, Making cellulose, converted to sucrose and transported to around the plant through Phloem

Petals in wind pollinated flowers

Dull

Transpiration

The loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata.

Effect of Oxygen in Seed Germination

Needed for aerobic respiration

Gravitropism

A response in which parts of a plant grow towards or away from gravity

Carpels

The female reproductive organ of a flower, consisting of the stigma, style, and ovary.

Increased Temperature

Increased Rate of Photosynthesis until a certain point

Nectar in wind pollinated flowers

None

balanced equation for photosynthesis

6CO2 + 6H2O ------> C6H12O6 + 6O2

Effect of Water in Seed Germination

Lets the seed swell and the embryo start to grow

Anthers

Contain pollen sacs. This is where pollen grains are formed. Pollen grains contain the male gametes (sex cells) required for fertilisation.

Stoma

allows gaseous exchange with surroundings ;

Wax cuticle

To protect the leaf without blocking out light.

Pathway of Water

Root hair cells => root cortex =>xylem vessels in the stems => to leaves

Phloem

Transport sugars and amino acids

Higher Temperature

lower transpiration rate. This is because water usually diffuses down a concentration gradient, but if the air outside is already saturated with water, there is more likely to be a net movement of water into the leaf (providing the stomata are open) rather than out.

Number of Pollen Grains in wind pollinated flowers

A lot

Photosynthesis

The process by which plants manufacture carbohydrates from raw materials using energy from light.

Pregnancy

More protein, calcium, vitamin D and iron for developing baby

Lipase

Breaks down fats to fatty acids and glycerol. Produced in the pancreas, mouth, and stomach.

Vitamin C

Growth and repair of tissues in all parts of your body

Males

Have higher energy needs

Peristalsis

Contracts and relaxing of muscles to push food

Young children

Need more protein and energy for growth and development

Lack of vitamin D

can lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones). It can also cause rickets.

Chemical digestion

Produces small, soluble molecules that can be absorbed

Egestion

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

Coronary heart disease

Too much saturated fat - causes plaques to form in arteries and they become narrower leading to angina and a heart attack 

Ingestion

The taking of substances, e.g. food and drink, into the body through the mouth

Obesity

Too much food especially fat and refined carbohydrates e.g. sugar 

Duodenum

The site of digestion in the small intestine

Constipation

Lack of fibre, may cause bowel cancer  

Vitamin D

Absorb calcium

Mouth

Technical digestion with teeth, chemical digestion with saliva 

Protease

Breaks down protein to amino acids. Made in the small intestine.

Salivary glands

Secret saliva

Large intestine

Water is absorbed here and the remaining waste material is stored as feces before being removed by defecation.

Digestion

The breakdown of large, insoluble food molecules into small, water- soluble molecules using mechanical and chemical processes

Mechanical digestion

The breakdown of food into smaller pieces without chemical change to the food molecules

Oesophagus

The swallowing of food causes it to move from the mouth to the stomach through the oesophagus, by peristalsis.

Rickets

A rare disease that causes the bones to become soft and bend.

Balanced diet

A diet that contains differing kinds of foods in certain quantities and proportions

Iron

Blood production

Fibre

Keep the digestive system healthy

Absorption

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

Proteins

Build up muscle

Scurvy

Insufficient vitamin C causes bleeding gums

Water

Help regulate temperature

Pancreas

Secretes pancreatic juices to the duodenum

Starvation

Lack of energy

Breast feeding

Requires more water

Lack of iron

Can't produce enough of a substance in red blood cells that enables them to carry oxygen.

Carbohydrates

Provide short term energy

Stomach

An organ containing gastric juices, chemically breaks down food

Amylase

Breaks down starch to simpler sugars. Produced by the salivary glands and the pancreas.

Fats

Provide long term energy

Calcium

Maintain strong bones

Malnutrition

The effect of incorrect amounts of the correct types of food on health 

Anus

Where the gastrointestinal tract ends and exits the body

Chemical digestion

The breakdown of large, insoluble molecules into small, soluble molecules

Gall bladder

Stores bile which is produced by the liver, and secretes it to the duodenum.

Hydrochloric acid

Kills bacteria in food and gives an acidic pH for enzymes

Pulmonary artery

Carries deoxygentated blood from the heart to the lungs

Atrial systole

Contraction of the atria, squeezing blood into the ventricles.

phagocytosis

White blood cells, process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

Vena cava

Returns deoxygenated blood to the right atrium of the heart.

Double circulation advantages

1. Higher blood pressure is maintained. Can create more pressure to pump blood round the whole body system.

2. There is a greater flow of blood to the tissues.

3. There is separation of oxygenated and deoxygenated blood.

4. Able to get blood to flow around the body faster.

Septum

Divides the right and left chambers of the heart

Double circulation

a circulatory system consisting of separate pulmonary and systemic circuits, in which blood passes through the heart after completing each circuit

Diastole

Relaxation of the heart, the atria are filled with blood.

Pulmonary vein

Deliver oxygen rich blood from the lungs to the left atrium

haemoglobin

The protein that carries oxygen in the red blood cells.

right ventricle

pumps deoxygenated blood to the lungs

Coronary arteries

blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle

veins

Blood vessels that carry blood back to the heart

Circulatory System

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

platelets

Make blood clots

arteries

Carry blood away from the heart

Aorta

The large artery that carries blood from the heart to be distributed by branch arteries through the body.

Ventricular systole

Contraction of ventricles, pumps blood into aorta and pulmonary arteries

Coronary heart disease

the blockage of coronary arteries and state the possible risk factors as diet, stress, smoking, genetic predisposition, age and gender

one way valves

Prevent backflow of blood

left ventricle

Pumps oxygenated blood into the aorta

white blood cells

Blood cells that perform the function of destroying disease-causing microorganisms

red blood cells

Blood cells that carry oxygen from the lungs to the body cells.

plasma

Liquid part of blood - transport of blood cells, ions, soluble nutrients, hormones and carbon dioxide

Muscular wall

A strong wall that separates the left side of the heart from the right side of the heart.

Atria

the two upper chambers of the heart- the receiving areas that pool incoming blood.

capillaries

Microscopic vessel through which exchanges take place between the blood and cells of the body. Diffusion.

hormone

a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs

role of the hormone adrenaline

chemical control of metabolic activity, including increasing the blood glucose concentration and pulse rate

adrenaline

the hormone secreted in 'fight or flight' situations and its effects, limited to increased breathing and pulse rate and widened pupils

uses of energy in the body

muscle contraction, protein synthesis, growth and the maintenance of a constant body temperature

lungs

two spongy organs, located in the thoracic cavity enclosed by the diaphragm and rib cage, responsible for respiration

Effects of physical activity on breathing

increased carbon dioxide concentration in the blood, causing an increased rate of breathing

tobacco

causes chronic obstructive pulmonary disease (COPD), lung cancer and coronary heart disease

inspired air

21% oxygen

-Low water vapour content

-Low carbon dioxide content

ciliated cells

can catch dust and microbes and move them out of the breathing system

bronchioles

smallest branches of the bronchi

larynx

voice box; passageway for air moving from pharynx to trachea; contains vocal cords

aerobic respiration

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

intercostal muscles

Muscles which move the rib cage during breathing

ribs

The bones in the chest that protect the heart and lungs.

alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

C6H12O6 + 6O2 → 6CO2 + 6H2O

balanced chemical equation for aerobic respiration

diaphragm

Large, flat muscle at the bottom of the chest cavity that helps with breathing

Gas exchange surfaces

large surface area, thin surface, good blood supply and good ventilation with air

bronchi

The passages that direct air into the lungs

trachea

a large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes and conveying air to and from the lungs; the windpipe.

word equation for aerobic respiration

glucose + oxygen → carbon dioxide + water

goblet cells

a column-shaped cell found in the respiratory and intestinal tracts, which secretes the main component of mucus.

expired air

17% oxygen

-High water vapour content

-High carbon dioxide content

mucus

a slimy substance produced in the nose and throat to moisten and protect them

sexual reproduction

a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other

asexual reproduction

a process resulting in the production of genetically identical offspring from one parent

ovaries

release of female gametes (eggs)

penis

transfers semen to vagina during sexual intercourse

cervix

ring of muscle at the opening of the uterus

urethra

carries urine and semen out of the body

scrotum

sac that holds the testes outside the body

fertilisation

as the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell/ovum)

testes

production of male gametes

uterus

where the fetus develops

sperm ducts

transfer sperm to the urethra

oviducts

transfers egg to uterus and the site of fertilisation

prostate gland

secrete fluids for sperm to swim in forming semen

vagina

receives penis during sexual intercourse

the dependence of the rate of diffusion on molecular mass

The speed at which a gas diffuses depends on how heavy its molecules are. Molecules that have a lower mass move faster than those with a higher mass. If the light and heavy molecules have the same amount of energy when they collide, the lighter ones will bounce off the heavier ones quicker, so lighter molecules diffuse faster than heavier molecules.

pressure and temperature of a gas 

The higher the temperature of a gas, the energy the particles have (on average). Therefore, they move faster and more and exert a greater pressure.

Liquids properties 

The particles are arranged randomly, yet are still connected. They can slide past each other and are still close. 

Brownian Motion

all tiny particles suspended in a fluid show irregular movement

Solids properties 

Particles have a fixed arrangement and position, are very close to each other and can only vibrate. 

Particle theory

When a substance is heated, we are essentially providing it with heat energy. As the particles of the substance absorb this energy, they move faster. When a substance is cooled, it loses its energy to its surroundings, so the particles move less.

Sublimation

solid to gas (directly, without melting then boiling)

kinetic particles theory

The idea that particles are constantly in motion

Gases properties 

The particles have a random arrangement, can more freely, and are spaced out and far apart from each other.

crystallisation

Used to produce solid crystals from a solution. When the solution is warmed, some of the solvent evaporates leaving behind a more concentrated solution. 

fractional distillation

The separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to fractionate.

Paper chromatography

The mixture is dissolved in a fluid (gas, solvent, water, ...) called the mobile phase, which carries it up the paper on which is fixed a material called the stationary phase.

RF value

The distance travelled by a given component divided by the distance travelled by the solvent front.

distillation

The process of separating components of a mixture based on different boiling points.

filtration

A process used to separate solids from liquids or gases using a filter medium that allows the fluid to pass through but not the solid.

chemical changes

change their chemical composition

Metal

an element that readily forms positive ions (cations) and has metallic bonds

Nonmetal

a chemical element (as boron, carbon, or nitrogen) that lacks the characteristics of a metal and that is able to form anions, acidic oxides, acids, and stable compounds with hydrogen.

mixtures

a material made up of two or more different substances which are physically combined

concentration

the abundance of a constituent divided by the total volume of a mixture

solution

a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent).

physical changes

Substances undergo a change that does not change their chemical composition.

elements

 a pure substance which cannot be broken down by chemical means

solute

the minor component in a solution, dissolved in the solvent.

solvent

able to dissolve other substances.

Compound

a substance that contains atoms of two or more different elements, and these atoms are chemically joined together

protons

+1 charge, weigh 1.67262 × 10⁻²⁷ kg

formation of ions

formed when atoms lose or gain electrons in order to fulfill the octet rule and have full outer valence electron shells

Electron shells

the outside part of an atom around the atomic nucleus. rings of up to 8 electrons, first shell is max 2 though

nucleon number (mass number)

the total number of protons and neutrons in the nucleus of an atom

structure of an atom

 a central nucleus, containing protons and neutrons, and ‘shells’ of electrons

lattice structure

a regular arrangement of alternating positive and negative ions, exemplified by the sodium chloride structure

electrons

-1 charge, 9.109×10⁻³¹ kilograms

noble gases

have complete outer shells, so they have no tendency to lose, gain, or share electrons

neutrons

0 charge, weigh 1.6749 × 10⁻²⁷ kg

formation of single covalent bonds

sharing of pairs of electrons leading to the noble gas configuration including the use of dot-and-cross diagrams

differences in solubility between ionic and covalent compounds.

Ionic compounds are usually soluble in water, unlike covalent compounds, which are less soluble.

differences in electrical conductivity between ionic and covalent compounds.

Ionic compounds can conduct electricity when melted or dissovled, and the lattice breaks up and ions are free to move. Covalent compounds are not charged, thus they do not conduct electricity.

differences in volatility between ionic and covalent compounds.

Covalent compounds have low melting and boiling points, unlike ionic bounds, which have high boiling and melting points. Thus covalent compounds are more volatile.

non-metallic elements

form simple molecules with covalent bonds between atoms

differences in melting point between ionic and covalent compounds.

 In order to melt an ionic compound, it is necessary to break ionic bonds.  Therefore, ionic compounds usually have high melting points.  To melt a covalent compound, it isn’t necessary to break bonds.  It is only necessary to overcome the much weaker intermolecular forces that hold the particles together.  Covalent compounds generally have much lower melting and boiling points than ionic compounds. 

anode

negative end of a terminal

cathode

positive end of a terminal

Molten lead(II) bromide

The electrolyte is molten PbBr2. It will discharge into Pb2+ ions and Br– ions.

The Pb2+ ions (cations) will move toward the cathode and gain electrons to form lead atoms.

The negative Br– ions (anions) will move toward the anode and lose electrons to form bromide atoms.

Pb2+(aq) +  2Br–(aq)  —> Pb(s) +  Br2

Dilute sulfuric acid.

Dilute sulfuric acid H2SO4 (aq). It contains water (H2O) as well. The ions present are H+, SO42-  and OH-.

There is only one positive ion that can discharge at the cathode and that is hydrogen. Hydrogen will undergo reduction (gain electrons) to become hydrogen atoms.

At the anion, OH will be discharged, as it is less reactive than the sulfate. OH will undergo oxidisation to lose electrons and become water and oxygen.

 electrode

solid electric conductor that carries electric current into non-metalls

electrolysis

the breakdown of an ionic compound when molten or in aqueous solution by the passage of electricity

inert electrode

an electrode that serves only as a source or sink for electrons without playing a chemical role in the electrode reaction.