Edexcel IGCSE Biology

Active transport

The movement of substances against a concentration gradient and/or across a cell membrane using energy

Anti Diuretic Hormone

Hormone which controls the selective reabsorbtion of water in Kidney

Aerobic Respiration

The process by which food molecules are broken down using oxygen to release energy for the cells

Allele

A version of a partivular gene

Anaerobic respiration

Cellular respiration in the absence of oxygen

Asexual reproduction

Reproduction which involves only one parent and produces offspring which are identical to their parents

Auxins

Plant hormones which are involved in controlling the phototropisms

Carbohydrates

Food group which includes the sugar and starches. They are important for providing energy for the cells

Cell

Basic unit of all living organism

Cellular respiration

Respiration which takes place in the cytoplasm and mitochondria of the cells

Cellulose cell wall

The rigid cell wall which surrounds plant cell

Chlorophyll

The green pigment contained in the chloroplast which captures light energy from the sun

Chloroplast

The plant organelles which contain chlorophyll. They are the site of photosynthesis

Clone

Offspring produces by asexual reproduction which are identical to their parent organism

Codominance

Two alleles which are both expressed in the phenotype of an offspring

Consumers

Organisms which feed on other organisms, eg. Primary eats plants, secondary consumers eat herbivores

Cytoplasm

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

Decomposers

Microorganisms that break down water products and dead bodies

Denatures

The breakdown of the structure of a protein molecule if the temperature gets too hot or the pH changes

Diastole

The stage of the cardiac cycle when the heart fills with blood-relaxation period of a heart beat

Differentiate

The process by which unspecialised cells become specialised for a particular function

Diffusion

The net movement of the particles of a gas or a solute from an area of high concentration to an area of low concentration, down a concentration gradient

Diploid

Having 2 sets of chromosomes in the nucleus of the cells: one from the male parent and one from the female

Disperse

The spreading of seeds away from the parent plant to avoid competition.

Dominant

A characteristic which will show up in the offspring even if only one of the alleles is inherited

Double circulation

The separate circulation of blood from the heart to the lungs and then back to the heart again and from the heart to the body and back to the heart again

Ecosystem

All of the animals and plants living in an area, along with the things what affect them, such as soil and the weather. An ecosystem includes all the interactions between the many different types of living organisms and the non-living components

Egestion

The removal of undigested food from a cell or from the body in the form of faeces

Endocrine glands

The glands which produce hormones and secrete them directly into the blood

Enzyme

A protein molecule which acts as a biological catalyst, speeding up the rate of a specific reaction without being used up or affected. Enzymes are sensitive to both temperature an pH

Eutrophication

When a lake or a river becomes enriched with nutrients, e.g from fertiliser applied to fields, excess plant growth is followed by decay. Microorganisms use up oxygen from the water so that other organisms can no longer survive

Fermentation

Another term for anaerobic respiration which is particularly used for microorganisms such as yeast. Glucose is partly broken down into ethanol or lactic acid with the release of a small amount of energy

Fertilisation

The joining of of the haploid male and female gametes to form a new diploid individual

Gametes

The haploid sex cell which contain only one set of chromosomes. Male gametes include sperm and pollen, female gametes include ova and ovules

Genetically modified organism

Organisms which have had DNA from a different species or a different individual inserted in their genome

Genotype

The genetic makeup of an organism concerning the alleles of a particular gene. e.g TT, Tt, tt

Global warming

An increase in the temperature at the surface of the earth due to green house gases in the atmosphere trapping infrared radiation from the surface

Glycogen

The carbohydrate energy store found in the liver and muscles of animals. It can be converted back into glucose when energy is needed in cells

Green house gases

Gases such as carbon dioxide and methane in the atmosphere which absorb infrared radiation from the surface of the Earth and radiate from the surface of the Earth and radiate it back to the surface, contributing to the greenhouse effect

Habitat

The place where an animal or plant lives including both the living and the non-living aspects of the area

Haploid

Having only one set of chromosomes in the nucleus of the cell

Heterozygous

When the two alleles for a particular gene on a pair of chromosomes are different e.e Tt

Homozygous

When the two alleles for a particular gene on a pair of chromosomes are the same, e.g TT tt

Hormones

Chemical messages which are secreted by endocrine glands and carried around the body in the blood to the organs they affect

Hypothalamus

The part of the brain which regulates many body functions, e.g temperature, thirst, hunger and sleeping. It also controls the production of many hormones from the pituitary glands

Invertebrates

Animals which do not have a backbone

Meiosis

A two-stage process of cell division which reduces the number of chromosomes from the diploid parent cell to the haploid daughter cell. It is important in the formation of gametes

Mitochondria

A cell organelle which is the site of aerobic respiration, so they produce most of the energy needed by the cell

Mitosis

Asexual cell division, a single-stage process which results in identical daughter cells

Natural selection

The processby which evolution happens. Organisms produce more offspring than the environment can support. Only those best adapted to their environment- the fittest- will survive to breed and pass on their characteritics

Neurone

The basic unit of the nervous system, they are cells which carry minute electrical impulses around the body

Nitrogen cycle

The continuous natural process by which nitrogen is exchanged between living organisms and the environment

Nucleus

The organelle in the cell which contains the genetic material

Organ

A group of different tissues working together to carry out a particular function in the body

Organ system

A group of organs working together to carry out a particular function in the body

Organelles

Membrane-bound structures found in the cytoplasm of a cell which carry out particular functions in the cells

Osmoregulation

The control and regulation of the levels of mineral ions and water in the cytoplasm of a cell or in the blood of an organism

Osmosis

The net movement of water down a concentration gradient from an area of high concentration of water molecules to an area of low concentration of water molecules across a partially permeable membrane

Phenotype

The physical characteristics of an organism with respect to one or more particular gene

Photosynthesis

The precess by which plants make food combining carbon dioxide and water to make glucose using light energy captured using chlorophyll

Phototropism

The response of a plant through growth using light shining from one side only

Plasmid

The extra circles of DNA containing genes found in bacteria and used by scientists in genetic enegineering

Population

A group of individuals of the same species living in the same habitat and breeding together

Positive tropism

A tropism (movement by growth) in which the plant moves towards a stimulus

Quadrat

A piece of equipment used to sample an area to investigate the size of a population of plants or slow moving animals. Quadrats are usually square frames of wood or metal that are laid on the ground to outline a sample area

Recessive

A characteristic which shows up on the offspring only when both of the alleles are inherited

Recombinant DNA

DNA which has had a section of DNA from another species or organism inserted into it

Sex chromosomes

The chromosomes whivh determine the sex of the offspring. In humans XX is female, XY is male

Sexual reproduction

Reproduction which involves the joining of two special haploid sex cells or gametes to produce diploid offspring which are genetically different from their parents

Synapse

The gap between two neurones where the transmission of the impulse is chemical rather than electrical. Transmission across the synapse on neurotransmitters

Systole

The stage of the cardiac cycle when the heart contracts and forces the blood out around the body and to the lungs

Transgenic

An organism which contains DNA from another organism

Transpiration

The loss of water vapour from the surface of the leaves of plants. Thnis occurs through the stomata when they are opened to allow gaseous exchange needed for photosynthesis to take place

Turgor

The state of a plant cell when water has moved in by osmosis so that the cytoplasm is pressing hard against the cellulose cell wall and no more wate can enter the cell

Umbilical cord

The structure that connects a fetus to the placenta. Food and oxygen travel from the mother to the developing fetus through the umbilical cord, waste products such as CO2 and urea pass in the other direction

Vaccination

Giving a dose of a weakened or dead pathogen (a vaccine) to stimulate the immune system to produce antibodies and develop immunity to a disease

Xylem

The transport tissue in plants which carries water and mineral ions up from the root through the stems to the leaves

Zygote

The new diploid individual formed when the haploid male and female gametes meet and fuse in sexual reproduction

Characteristics of living organisms

MRS.GRENC

Animal Cell structures

Cell membrane, cytoplasm, nucleus and mitochondria

Plant cell structure

Cell walls, permanent vacuole, chloroplast, cell membrane, cytoplasm, nucleus and mitochondria

What are enzymes

Biological catalyst in metabolic reactions

What are enzymes affected by

temperature and pH

How does substances move in and out of cells

Diffusion, osmosis, active transport

A catalyst

speeds up reactions without being used or changing the reaction

What are enzymes made of

Protein

What is substrate attached to

active site of enzymes

How are enzymes denatured

by anything that changes the shape of active sites

What do the shape of active site depend on

the shape of protein molecules, temp and pH

Cellular respiration

break down food to release stored chemical energy

Formula for aerobic respiration

C6H12O6 + 6O2 --> 6CO2 + 6H20 + energy

What uses chemical energy

muscle contraction, active transport, building up large molecule and cell division

What is aerobic respiration

use energy to oxidise food, CO2 and H20 released as waste

What is anaeorobic respiration

Glucose isnt completely broken down, less energy released

Anaerobic for yeast

Glucose--> ethanol+Carbon dioxide

Anaerobic for animals

Glucose--> lactic Acid

Formula for glucose

C6H12O6

Oxygen debt is

the amount of oxygen needed to break down lactic acid in muscles

What to use when testing for heat production during respiration

using germinating peas in vacuum flasks

What is diffusion

Is the net overall movement of particles from a high concentration to a lower concentration