Old and New Species

endemic

When a species evolves in isolation and is found in only one place in the world; it is said to be endemic (particular) to that area.

environmental isolation

This is when the climate changes in one area where an organism lives but not in others.

extinction

Extinction is the permanent loss of all members of a species.

geographical isolation

This is when two populations become physically isolated by geographical features.

speciation

The formation of a new species.

Simple Inheritance in Plants and Animals

cystic fibrosis

A genetic disease that affects the lungs, digestive and reproductive systems. It is inherited through a recessive allele.

differentiated

Specialised for a particular function.

allele

A version of a particular gene.

DNA fingerprint

Pattern produced by analysing the DNA which can be used to identify a person.

asexual budding

A form of asexual reproduction where a complete new individual forms as a bud on the parent organism e.g. yeast, hydra.

genetic material

The DNA which carries the information for making a new cell or individual.

carrier

Individual who is heterozygous for a faulty allele that causes a genetic disease in the homozygous form.

genetic disorders

Diseases which are inherited.

meiosis

The two stage process of cell division which halves the number of chromosome number in daughter cells. It is involved in making the gametes for sexual reproduction.

mitosis

Asexual cellular division where two identical cells are formed.

ovum

Female sex cell.

polydactyly

A genetic condition inherited through a dominant allele which results in extra fingers and toes.

protein synthesis

The process by which proteins are made on the ribosomes based on information from the genes.

recessive

The characteristic that will show up in the offspring only if both of the alleles are inherited.

ribosomes

The site of protein synthesis in a cell.

sex chromosomes

The chromosomes which carry information about the sex of an individual.

stem cells

Undifferentiated cells with the potential to form a wide variety of different cell types.

therapeutic cloning

Cloning by transferring the nucleus of an adult cell to an empty egg to produce tissues or organs which can be used in medicine.

Energy from Respiration

mitochondria

Organelle which is the site of aerobic respiration.

oxygen debt

The extra oxygen that must be taken into the body after exercise has stopped to complete the aerobic respiration of lactic acid.

aerobic respiration

Breaking down food using oxygen to release energy for the cells.

respiration

The process by which food molecules are broken down to release energy for the cell.

anaerobic respiration

Breaking down food without oxygen to release energy for the cells.

lactic acid

One product of anaerobic respiration. It builds up in muscles with exercise. 

Important in yoghurt and cheese-making processes.

Enzymes

bile

Yellowy-green liquid made in the liver and stored in the gall bladder. It is released into the small intestine and emulsifies fats.

biological detergent

Washing detergent that contains enzymes.

carbohydrase

Enzyme which speeds up the breakdown of carbohydrates.

catalyst

A substance which speeds up a chemical reaction. At the end of the reaction the catalyst remains chemically unchanged.

activation energy

The minimum energy needed to start off a reaction.

active site

The site on an enzyme where the reactants bind.

amino acid

The building block of protein.

amylase

The enzyme made in the salivary glands and the pancreas which speeds up the breakdown of starch into simple sugars.

denatured

Change the shape of an enzyme so that it can no longer speed up a reaction.

digested

Broken down into small molecules by the digestive enzymes.

digestive juices

The mixture of enzymes and other chemicals produced by the digestive system.

emulsifies

Breaks down into tiny droplets which will form an emulsion.

enzyme

A protein molecule that acts as biological catalyst.

fatty acids

An acidic building block of lipids.

glycerol

A neutral building block of lipids.

Glycogen

Carbohydrate store in animals, including the muscles, liver and brain.

isomerase

An enzyme which converts one form of a molecule into another.

lipase

Enzyme which breaks down fats and oils into glycerol and fatty acids.

lipids

Fats and oils.

protease

An enzyme which breaks down protein.

salivary glands

Glands in the jaw which secrete salivary amylase.

substrate

The material or molecule upon which an enzyme acts.

Organisms in the Environment

cellulose

A big carbohydrate molecule which makes up plant and algal cell walls.

limiting factors

Factors which limit the rate of reaction. e.g. temperature, pH, light levels (photosynthesis).

hydroponics

Growing plants suspended in water enriched with mineral ions rather than soil.

bacterial colony

A population of billions of bacteria grown in culture.

glucose

A simple sugar.

algal cells

The cells of algae, single-celled or simple multicellular organisms, which can photosynthesise but are not plants.

mineral ions

The chemicals needed in small amounts by living organisms.

nitrate ions

Mineral ions which are needed by plants to make proteins.

polytunnels

Large greenhouses made of plastic.

predator

An animal which eats other animals.

quadrat

A piece of apparatus for sampling organisms in the field.

quantitative sampling

Sampling which records the number of organisms and not just the type.

transect

A measured line or area along which ecological measurements (e.g. quadrats) are made.

tubers

Modified parts of a plant which are used to store food in the form of starch.

variegated

Having different colours e.g. a green and white leaf.

Cells, Tissues and Organs

cell membrane

The membrane around the contents of a cell which controls what moves in and out of the cell.

cell wall

A rigid structure which surrounds the cells of living organisms apart from animals.

cytoplasm

The water-based gel in which the organelle of all living cells are suspended.

concentration gradient

The gradient between an area where a substance is at a high concentration and an area where it is at a low concentration.

diffusion

The net movement of particles of a gas or a solute from an area of high concentration to an area of low concentration (along a concentration gradient).

digestive system

The organ system running from the mouth to the anus where food is digested.

epidermal tissue

The tissue of the epidermis - the outer layer of an organism.

epithelial tissue

Tissue made up of relatively unspecialised cells which line the tubes and organs of the body.

glandular tissue

The tissue which makes up the glands and secretes chemicals e.g. enzymes, hormones.

mesophyll tissues

The tissues in a plant in which photosynthesis occurs.

multicellular organism

An organism which is made up of many different cells working together. Some of the cells are specialised to carry out particular functions.

light microscope

An instrument used to magnify specimens using lenses and light.

chlorophyll

The green pigment contained in the chloroplasts.

net movement

The overall movement of...

chloroplast

The organelle in which photosynthesis takes place.

muscular tissue

The tissue that makes up the muscles. It can contract and relax.

nucleus

An organelle found in many living cells. It contains the cell's genetic information.

organ

A group of different tissues working together to carry out a particular function.

organ system

A group of different organs working together to carry out a particular function.

permanent vacuole

A space in the cytoplasm filled with cell sap that is present all the time.

phloem tissues

The living transport tissue that carries sugars around plants.

plasmids

Extra circles of DNA found in bacterial cytoplasm.

small intestine

The region of the digestive system where the majority of digestion occurs.

specialised

Adapted for a particular function.

tissue

A group of specialised cells all carrying out the same function.

xylem tissue

The non-living transport tissue in plants, which transports water around the plant.

Nutrient Recylcing

Denitrifying bacteria

Bacteria that convert nitrates into atmospheric nitrogen

Nitrifying bacteria

Bacteria that convert ammonia into nitrates

Nitrogen fixing bacteria

Bacteria that live in the root nodules of legumes, which convert atmospheric nitrogen into nitrates for the plant to use

Nitrogen fixing bacteria convert atmospheric nitrogen into nitrates, nitric acid formed in thunderstorms

Processes that take nitrogen out of the air

Volcanic gases, decay and respiration, burning of fossil fuels

Process that put carbon into the atmosphere

Photosynthesis, carbonate rock, dissolves into oceans

Things that take carbon out of the atmosphere

Pollution and Pollution Indicators

Problems of a growing human population

Non-renewable resources are used up more quickly, more waste is produced, more pollutants (e.g phosphates, nitrates, sulfur dioxide) are produced

Eutrophication

When fertilisers from farms are leached into rivers, causing algal bloom, causing organisms to die

Pollutants

Substances that have a negative impact on water, air or land

Indicator species

Species that give scientists information about the environment they're in (e.g the presence of pollutants)

Lichens, blackspot fungus on rose leaves

Indicator species for unpolluted air

Stonefly larvae, freshwater shrimps

Indicator species for unpolluted water

Blood worms, sludgeworms

Indicator species for polluted water

Interdependence

Pyramid of Biomass

Pyramid which shows the total dry mass of organisms at each trophic level

Pyramid of number

Pyramid which shows the number of organisms at each trophic level

Mutualism

An relationship in which both organisms benefit

Parasites

Organisms which live on a host and benefit from the host, but the host is damaged

Parasitism examples

Dog & fleas, head lice & human, tapeworm & human, mistletoe & tree

Mutualism examples

Oxpecker & buffalo, cleaner fish & large fish, nitrogen-fixing bacteria & legume, chemosynthetic bacteria & giant tubeworms

Pathogens and Diseases

Bacteria

Single celled organism, bigger than viruses, smaller than fungi

Viruses

Extremely small, not whole cells. They reproduce inside other cells, and are not really alive

Fungi

Reproduce by producing spores, some types can causes infections such as athlete's foot

Protozoa

Single celled organism with a nucleus

Pathogens

Harmful micro-organisms

Examples of pathogens spread through water

Cholera, typhoid fever

Examples of pathogens spread through food

Salmonella, E.Coli

Examples of pathogens spread through air

Influenza virus, chickenpox

Example of a pathogen spread through contact

Athlete's foot

Examples of pathogens spread through body fluids

HIV, or any other STI

Examples of pathogens spread through animal vectors

Protozoan (that causes malaria), 

salmonella

Animal vectors

Animals which spread 

Physical human barriers to pathogens

Skin, respiratory tract is lined with mucus that traps pathogens

Chemical human barriers to pathogens

Tears, contain a chemical called lysozyme that kills bacteria, stomach contains hydrochloric acid

Infectious diseases

Diseases caused by pathogens which are transmitted from one host to another

Antibiotics

Drugs that inhibit or destroy bacteria and fungi

Antibacterials

Drugs that kill bacteria or stop them from growing

Antifungals

Drugs that kill fungi or stop them growing

Antiseptics

Drugs that are used outside the body to preven infection by stopping bactieral growth or destroying bacteria

MRSA

A resistant strain of bacteria that has evolved resistance to antibiotics

Drugs

Drug

A natural or synthetic substance or chemical that affects the central nervous system

Addictive

Your body is physically dependent on it

Reaction time

The time it takes you to respond to a stimulus

Liver cirrhosis

Over-consumption of alcohol causes the death of liver cells, forming scar tissue that blocks blood flow. This leads to toxic substances building up in the body.

Jaundice

Yellowing of eyes and skin

Painkillers

Decrease the feeling of pain, work by blocking nerve impulses in the brain

Depressants

Decrease brain activity. Cause depressed heart rate and respiration, slowed reflexes, nausea and vomiting, suppression of pain, slow & slurred speech

Stimulants

Increase brain activity by increasing the amount of neurotransmitter released into neurone synapses. Cause increased heart rate and breathing rate, speed up reflexes, make you feel alert

Hallucinogens

Distort what you see and hear by altering the pathways nerve impulses usually travel along.

Short-term effects of alcohol

Slower reflexes, blurred vision, lower inhibitions

Long-term effects of alcohol

Liver cirrhosis, reduced fertility, brain damage

Examples of painkillers

Morphine, paracetomol, aspirin

Examples of stimulants

Cocaine, caffeine, nicotine, amphetamines, speed

Examples of depressants

Heroin and alcohol

Examples of hallucinogens

LSD, magic mushrooms

Nicotine

An addictive chemical that raise the heart beat, narrows arteries and so causes high blood pressure, leading to heart disease

Tar

Coats the lining of the lungs making them less able to take in oxygen, and also contains carcinogens

Carbon monoxide

A poisonous gas which reduces the capacity for red blood cells to carry oxygen by attaching to haemoglobin

Plant Growth Hormones

Tropisms

Plant growth responses

Positive tropism

Growth towards a stimulus

Negative tropism

Growth away from a stimulus

Phototropism

A growth towards light

Gravitropism

A growth downwards (positive) or upwards (negative) in response to gravity

Auxins

Plant growth hormones which control growth at the tips of shoots and roots

Gibberellins

Plant growth hormones which stimulate seed germination, stem growth and flowering

Uses of gibberellins

Weedkillers, rooting powder for currings, controlled ripening of fruits while in transportation or in shops, applying them to unpollinated flowers so the fruit grows but not the seeds

Hormones & Diabetes

Pancreas

An endocrine gland: controls blood sugar levels using insulin and glucago.

Adrenal glands

An endocrine gland: Produce adrenaline to speed up the heart rate and speed up responses to stimuli

Pituitary gland

An endocrine gland: release anti-diuretic hormone (ADH) which conserves water in the body by making the kidneys produce more concentrated urine

Testes

Male endocrine glands: release testosterone which causes the development of male reproductive organs during puberty

Ovaries

Female endocrine glands: produce oestrogen which causes the development of female reproductive organs during puberty

Hormones

Chemicals released by endocrine glands which regulate processes in the body

Target organ

An organ that responds to a certain hormone

Insulin

A hormone released by the pancreas which reduces the blood sugar level by causing the liver to turn glucose into glycogen

Glycogen

A store of glucose in the liver

Glucagon

A hormone released by the pancreas which increases the blood sugar level by causing the liver to turn glycogen into glucose

BMI

A measurement that uses a person's weight and height to determine if they are of a healthy weight

Endocrine glands

Parts of the body which produce hormones

Type 1 diabetes

The pancreas doesn't produce enough (or any) insulin. Is controlled by injecting manufacture insulin to reduce the blood sugar level, and avoiding foods that contain lots of glucose

Type 2 diabetes

Either cells/target organs don't respond to insulin, or the person becomes immune to the effects of the hormone. Is controlled by eating a healthy diet, having regular exercise and losing weight. Some

The Nervous System

Sense organs

Organs that detect stimuli that you need to react to, e.g eyes, ears

Stimulus

A change in the environment

Receptors

Groups of cells in sense organs which are sensitive to stimuli, and convet stimulus energy to electrical energy

Effectors

Muscles and glands that carry out the necessary change

Response

The result of the action of the effector (e.g body temperature returning to 37 degrees)

Central Nervous System

The brain and the spinal chord

Neurones

Nerve cells which transmit nerve impulses

Sensory neurones

Carry nerve impulses from the receptors to the CNS. They have long dendrons and short axons

Motor neurones

Carry nerve impulses from the CNS to the effectors. Many short dendrons and one long axon

Relay neurones

Carry nerve impulses inside the CNS from sensory neurones to motor neurones. Short dendrons and axons.

Dendrons

Branches which carry nerve impulses towards the cell body

Dendrites

The tiny branches of dendrons which are connected to cells

Axons

Branches which convey the electrical impulses away from the cell body

Myelin sheath

Insulating envelope that surrounds an axon

Synapse

A small gap where one neurone connects to another

Neurotransmitters

Chemicals that transmit impulses across synapses

Reflexes

Automatic responses to stimuli

Reflex arc

When nerve impulses travel straight from the receptors to the CNS to the effector, bypassing the brain. A reflex reaction.

Homeostasis

Homeostasis=

Maintaining a stable internal environment

Thermoregulation=

The regulation of body temperature

Glucoregulation=

The regulation of blood-glucose levels

Osmoregulation=

The regulation of water in the body

Negative feedback=

The process by which homeostasis works: stimulus - receptor - control centre - effector - response

Hypothalamus=

The part of the brain which controls body temperature and other things

Vasodilation=

Blood vessels close to the surface of the skin widen (in order to lower body temperature)

Vasoconstriction=

Blood vessels close to the surface of the skin contract (in order to reduce heat loss, to warm up)

Genetic Crosses and Disorders

Genotype=

The combination of genes you inherit for a specific characteristic

Phenotype=

The observable appearance of a characteristic

Dominant=

Type of allele: will result in the characteristic being expressed whether you have 1 or two copies of the allele

Recessive=

Type of allele: will only result in the characteristic being expressed if you have both copies of the allele

Gametes=

Sex cells

Homozygous=

Two of the same alleles of a gene

Heterozygous=

Two different alleles of a gene

Cystic Fibrosis=

A recessive disease

Sickle Cell Anaemia=

A co-dominant disese

Cystic fibrosis cause=

The body produces lots of thick sticky mucus which blocks the air passages, gut and pancreas

Sickle Cell Anaemia Cause=

Red blood cells are sickle shaped and block capillaries

Cystic fibrosis symptoms=

Breathing difficulties, lung infections, malnutrition, infertility

Sickle cell anaemia symptoms=

Tiredness, painful joints and muscles, fever, anaemia, jaundice

Natural Selection, Speciation Extreme

Natural Selection

The process where the best adapted organisms survive, reproduce and pass on their genes

Evolution

When the long term effects of natural selection leads to a characteristic becoming common place in a population

Adaptations

Beneficial features that help an organism to survive

Resistance

The ability to be unaffected by disease or poison

Speciation

When the long term effects of evolution lead to the creation of a new species, that is so genetically different that it can no longer successfully reproduce with its founder species

Reproductive Isolation

When organisms are blocked from reproducing by a physical barrier

Gene

A section of DNA that codes for a specific protein

Nucleus

The part of the cell that contains genetic information

Chromosome

1 molecule of DNA coiled up

Alleles

Different versions of the same gene.

Genetic variation

Genetic variation

Variation that is inherited from an organism's parents

Environmental variation

Variation caused by an organism's lifestyle and surroundings

Continuous variation

A feature for which individuals in a population vary within a range. There are no distinct categories.

Discontinuous variation

A feature for which individuals in a population fall in to distinct categories.

Normal distribution curve

AKA bell curve: a graph that shows continuous variation. Two extremes, with most people falling in the middle.

The Classification of Species

Animalia

A kingdom of organisms: multicellular, no cell wall, heterotrophic, have nucleus in cells.

Plantae

A kingdom of organisms: multicellular, have chlorophyll, have cell walls, autotrophic, photosynthesise, cell have a nucleus.

Fungi

A kingdom of organisms: multicellular, have cell walls, saprophytic, cells have a nucleus.

Protoctista

A kingdom of organisms: usually unicellular, cells have a nucleus.

Prokaryotes

(AKA bacteria) A kingdom of organisms: unicellular, no nucleus.

Species

A group of organisms with similar characteristics, which can successfully interbreed to produce fertile young.

Heterotrophic

Get energy from other organisms

Autotrophic

Makes its own food

Saprophytic

Feeds off dead and decaying matter

Binomial system

The system scientists use to name species, it consists of two latin names: the first is the genus, the second is the species. The genus starts with a capital letter but the species name doesn't.

Ring species

A group of related populations that live in a ring. Neighbouring populations can interbreed to produce fertile offspring, but populations that live firth apart cannot.

Oviparous

Lays eggs

Viviparous

Gives birth to live young

Homeothermic

Keeps its body temperature at a constant level

Poikilothermic

Body temperature varies with the organism's surroundings

Mammals

A class of choredate: has lungs, are viviparous, are homeothermic

Birds

A class of chordate: has lungs, are oviparous, are homeothermic

Fish

A class of chordate: has gills, are mostly oviparous, are mostly poikilothermic

Reptiles

A class of chordate: have lungs, are oviparous, are poikilothermic

Amphibians

A class of chordate: absorb oxygen through their skin, are oviparous, are poikilothermic