Science Yr7

Definition of digestion:

The breakdown of large insoluble food molecules into smaller soluble ones.

Definition of digestive system:

Organ system involved in breaking food down so that it can be absorbed into the bloodstream.

Definition of absorbed:

When a substance is taken in by something or moved across a barrier such as a cell membrane.

Definition of amylase:

An enzyme that can break down starch into simple sugars.

Definition of lipase:

Enzyme that breaks down lipids (fats & oils).

Definition of carbohydrase:

Enzyme that breaks down carbohydrates.

Definition of protease:

Enzyme that breaks down proteins.

Definition of enzyme:

A protein which catalyses or speeds up a chemical reaction.

Definition of surface area:

The area of the surface of an organism or membrane.

Definition of villi:

Finger-like projections in the small intestine that provide a large surface area for the absorption of food.

Definition of capillary:

Tiny blood vessels with walls one-cell thick where exchange of materials occurs.

Definition of bile:

Substance produced in the liver. It emulsifies fats to prepare them for digestion.

Definition of pancreas:

Produces biological catalysts called enzymes which speeds up the digestive reactions.

Definition of excretion:

Process by which waste products from chemical reactions in an organism are removed.

Definition of oesophagus:

Connects the mouth to the stomach. Food is pushed down using contractions of muscles.

Definition of liver:

Production of bile.

Definition of stomach:

Churns and mixes the food with hydrochloric acid and enzymes.

Definition of small intestine:

Absorption of digested food into the bloodstream, production of enzymes to aid digestion.

Definition of large intestine:

Absorption of excess water.

Definition of rectum:

Storage of faeces before excretion.

Definition of anus:

Where faeces are excreted.

Definition of cell:

Basic unit of life.

Definition of cell membrane:

Controls the movement of substances in and out of the cell.

Definition of cytoplasm:

Jelly-like substance where chemical reactions take place.

Definition of nucleus:

Carries genetic information and controls the cell.

Definition of mitochondria:

Where respirationDefin

Definition of cell wall:

Made of cellulose, provides support to the cell.

Definition of vacuole:

Contains cell sap.

Definition of chloroplast:

Contains the green pigment chlorophyll, the site of photosynthesis.

Definition of tissue:

Something made from just one type of specialised cell.

Definition of organ:

Something made from different groups of specialised cells all working together.

Definition of organ system:

When a number of organs work together.

Definition of synovial joint:

A freely moveable joint.

Definition of light microscope:

A device which uses light and a series of lenses to produce a magnified image of an object.

Definition of magnification:

How much bigger a sample/object appears under the microscope than it is in real life.

Definition of total magnification:

Eyepiece lens x Objective lens

Definition of red blood cell:

Carries blood around the body.

Definition of sperm cell:

Carries the male genes.

Definition of root hair cell:

Take in water from the soil.

Definition of palisade cell:

Production of food for the plant.

Definition of nerve cell:

Carries signals around the body.

Definition of egg cell:

The female sex cell.

Definition of magnification:

Eyepiece lens x Objective lens

Definition of diffusion:

The movement of particles from an area of high concentration to an area of low concentration.

Definition of respiration:

Process in living things which oxygen is used to release the energy from food.

Definition of aerobic respiration:

Respiration that requires oxygen.

Definition of anaerobic respiration:

Respiration without oxygen.

Definition of lactic acid:

A chemical produced during anaerobic respiration.

Definition of mitochondria:

Structures in the cytoplasm of all cells where aerobic respiration takes place.

Definition of oxygen debt:

The amount of extra oxygen required by the body for recovery after vigorous exercise.

Definition of alveoli:

Tiny air sacs in the lungs, where gas is exchanged during breathing.

Definition of bronchi:

Branches off the trachea that distribute air to both lungs.

Definition of bronchioles:

Branches of the bronchi, that distribute the inhaled air throughout all of the lungs.

Definition of diaphragm:

 A muscle that helps you inhale and exhale.

Definition of lungs:

Soft organ that inflates to draw in oxygenated air and deflates to expel air.

Definition of trachea:

Windpipe, air passes between mouth and lungs.

Definition of sperm cell:

The male sex cell.

Definition of fertilisation:

The fusing of the male and female sex cells.

Definition of ovary:

The female reproductive organ that releases egg cells.

Definition of testes:

The male reproductive organs which produce sperm cells.

Definition of embryo:

Tiny new human life which grows by cell division from a fertilised egg cell.

Definition of gestation:

The period between fertilisation and birth.

Definition of placenta:

The organ that allows substances to pass between the mothers blood and baby's blood.

Definition of amniotic fluid:

A fluid which surrounds the fetus and helps to cushion it.

Definition of fetus:

The unborn baby after around 8 weeks of pregnancy.

Definition of menstruation:

Where the lining of the uterus breaks down every month if the egg is not fertilised.

Definition of sexual reproduction:

Producing new organisms by the joining of two sex cells.

Definition of asexual reproduction:

Producing new organisms from only one parent.

Definition of photosynthesis:

Process carried out where plants make their own food.

Definition of chlorophyll:

Green pigment in chloroplasts of plant cells. It enables photosynthesis to take place.

Definition of chloroplasts:

Contain the green pigment chlorophyll, the site of photosynthesis.

Definition of waxy cuticle:

Waxy layer, prevents water loss.

Definition of upper epidermis:

Thin and transparent allowing light to pass through.

Definition of palisade mesophyll:

Main region for photosynthesis. Lots of palisade cells containing lots of chloroplasts.

Definition of spongy mesophyll:

Cells are more loosely packed. Contains air spaces between cells allowing gas exchange.

Definition of lower epidermis:

Contains stomata to regulate the loss of water vapour.

Definition of stomata:

Each stomata is surrounded by a pair of guard cells. Guard cells control whether they’re open or closed.

Definition of petals:

Brightly coloured to attract insects.

Definition of stamen:

The male part of the flower.

Definition of stigma:

The top of the female part of the flower which attracts pollen.

Definition of anthers:

Produce make sex cells.

Definition of nectary:

Produces a sugary solution called nectar, which attracts insects.

Definition of nucleus:

Controls what happens inside the cell.

Definition of DNA:

Carries the genetic information of a living being.

Definition of double helix:

The shape of DNA molecule with two strands twisted together in a spiral.

Definition of base pair:

The pair of nitrogenous bases that connects the complementary strands of DNA.

Definition of bond:

The chemical link that holds molecules together.

Definition of gene:

A section of DNA which controls part of a cells chemistry.

Definition of heredity:

Genetic information that determines an organisms characteristics.

Definition of variation:

Difference between individuals.

Definition of continuous variation:

Variation that shows a wide range of intermediate values between two extremes.

Definition of discontinuous variation:

Differences between individuals in a characteristic that can only be put into different categories.

Definition of environmental variation:

Differences between individuals of a species due to factors in their surroundings.

Definition of acidic:

Having a pH lower than 7.

Definition of alkali:

A base which is soluble in water.

Definition of alkaline:

Having a pH greater than 7.

Definition of base:

A substance that reacts with an acid to neutralise it and produce a salt.

Definition of neutralise:

To be make neutral by removing any acidic or alkaline nature.

Definition of neutral:

When a substance is neither acidic nor alkaline and has a pH of 7.

Definition of litmus paper:

An indicator that can be red or blue.