2. Structure and function of living organisms

Organelle

A tiny cell structure that carries out a specific function within the cell

Cell

smallest unit of life

Tissue

A group of similar cells that perform the same function.

Organ

A collection of tissues that carry out a specialised function of the body

Organ system

group of organs that work together to perform a specific function

contract

Become shorter. Muscles contract and relax to allow movement.

magnification

The amount that an image of something is scaled up when viewed through a microscope.

organism

Living entity, eg animals, plants or microorganisms.

vacuole

A space within the cytoplasm of plant cells that contains cell sap.

Cytoplasm

A jellylike fluid inside the cell where most of the chemical reactions happen

Nucleus

Contains genetic material which controls the cell's activities

Cell membrane

Controls the movement of substances in and out of the cell

Mitochondria

Where most energy is released in respiration

Ribosome

Where protein synthesis happens

Chloroplasts

Absorb light energy for photosynthesis

Cell wall

Strengthens the cell and supports the plant

Permanent vacuole

Filled with cell sap to help keep the cell turgid

Specialised cells

Cells that are adapted to carry out a particular function

protein fibres

Cells in muscle that can contract (become shorter)

Cilliated cells

Cells with little "hairs" on them. Help move things along your trachea

Red Blood Cells (RBC) function

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

Red Blood Cells (RBC) structure

Cells that contain haemoglobin, have no nucleus, is biconcave and flexible

Root hair cell function

Absorbs water and mineral ions from the soil.

Root hair cell adaptations

Large surface area to volume ratio, long thin extension, no chloroplasts

Xylem vessel function

transports water in the plant, supports the plant

Xylem vessel adaptations

Strong, water proof cell walls. Form a continuous tube.

Calculating Magnification

size of image / actual size of specimen

Calculating actual size of a biological specimen

Measured size / magnification

concentration gradient

The difference in the concentration of a chemical across a membrane.

cytoplasm

The living substance inside a cell (not including the nucleus).

diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration.

glucose

C6H12O6. A simple sugar used by cells for respiration.

isotonic

Two solutions at the same concentration. An equal amount of water is entering and exiting the cell

mass

The amount of matter an object contains. Mass is measured in kilograms (kg) or grams (g).

osmosis

The movement of water molecules across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration.

partially permeable

Also called semi-permeable. A partially permeable membrane allows water and other small molecules to pass through, but not larger molecules such as starch.

respiration

The chemical change that takes place inside living cells, which uses glucose and oxygen to release the energy that organisms need to live. Carbon dioxide is a by-product.

Solute

The dissolved substance in a solution.

solvent

The liquid in which the solute dissolves to form a solution.

sucrose

A disaccharide made from glucose and fructose. It is used as table sugar.

turgid

Enlarged and swollen with water. Having turgor. Description of a plant cell in which the vacuole has swollen due to water gain by osmosis.

Villi

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

diffusion distance

the greater the distance over which diffusion must occur. The longer it takes, the lower the process.

SA:Vol

surface area to volume ratio

surface area to volume ratio

Ratio of a cell's outside area to its internal volume. A large number means the cell can quickly absorb.

kinetic energy

energy due to motion

active transport

the movement of molecules from low concentration to high concentration against the concentration gradient.

Energy

ATP

Flaccid

Lacking firmness. Soft and drooping because of lack of water.

Plasmolysis

This happens when a cell shrinks inside its cell wall while the cell wall remains intact.

cell membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

abiotic factors

Nonliving components of environment. Temperature, nutrients, pH.

John wanted to investigate the effect of the size of potato tissue on the rate of osmosis. He cut three different sized cubes of potato, one 0.5 × 0.5 x 0.5 cm, one 1 × 1 × 1 cm

and one 2 × 2 × 2 cm.

He weighed the potato cubes and recorded their masses.

He then placed each cube into a beaker of distilled water and left them for 1 hour. He weighed them again and recorded their new masses.

In each case the mass of the potato cubes increased.

Use your knowledge of osmosis to explain why the mass of each cube increased

water enters / water in / eq;

dilute to more concentrated solution / eq;

partially permeable membrane / eq;

Explain the effect of the different SA:Vol ratios on the rate of osmosis into the potato

more osmosis / faster (small cubes) / greater % increase / greater % change / eq;

larger SA:Vol ratio (of small cubes)

What is meant by the term diffusion

movement of molecules/particles/gases/named molecule;

high conc. to low conc. / down concentration gradient / eq;

Respiration takes place in the middle piece of the sperm cell. Explain why respiration is important to a sperm cell

energy / ATP;

swim / move / move tail / travel

What is meant by the term osmosis

1. water;

2. dilute solution to concentrated solution /

high conc. (of water) to low conc. (of water) / eq;

3. selectively permeable membrane / eq;

Explain why the cells in distilled water look different when compared to the cells in salt solution.

(in distilled water)

1. water into cells;

2. outside solution/distilled water more dilute

/ down concentration gradient / eq; 3. cell membrane against cell wall / eq; 4. turgid;

(allow converse in salt solution for each point)

1. water leaves cell;

2. outside solution/distilled water less

concentrated / eq;

3. cell membrane shrinks away from cell wall

/eq

4. plasmolysed / flaccid;

If red blood cells are placed in distilled water and examined under a microscope no cells are seen.

Explain why no red blood cells would be seen.

1. water into red blood cell / eq;

2. cells burst / haemolysis / eq;

3. no cell wall;

What is meant by the term anaerobic?

No oxygen

Write the word equation for the anaerobic respiration of yeast

Glucose = carbon dioxide + ethanol

aerobic respiration

Aerobic respiration is a chemical reaction that requires oxygen and transfers energy to cells.

alveoli

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

anaerobic respiration

Respiration that occurs in the absence of oxygen.

Bronchi

The plural of 'bronchus'. The bronchi are the two major air tubes in the lungs.

Bronchioles

The many small, branching tubules into which the bronchi subdivide.

Diaphragm

A large sheet of muscle that separates the lungs from the abdominal cavity.

Diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration.

exhale

to breathe air out of the lungs

Fermentation

Type of anaerobic (no oxygen) respiration carried out by yeast.

gas exchange

Oxygen passes through the capillary wall and into the tissues; carbon dioxide passes from the tissues into the blood.

inhale

to breathe air into the lungs

intercostal muscles

Sets of muscles between the ribs which raise and lower the rib cage.

lactic acid

A toxic chemical produced during anaerobic respiration.

lungs

The organs responsible for gas exchange in mammals, birds, reptiles and amphibians.

mitochondria

Structures in the cytoplasm of all cells where aerobic respiration takes place (singular is mitochondrion).

respiration

The chemical change that takes place inside living cells, which uses glucose and oxygen to release the energy that organisms need to live. Carbon dioxide is a by-product of respiration.

respiratory system

The organ system where air is taken into and out of the body, and gas exchange happens.

trachea

The windpipe, the tube that leads from the mouth towards the lungs.

unicellular

A single-celled organism.

ventilation

Breathing in and out.

Mitochondrion

Site of ATP (energy) production

TERM

active site

DEFINITION

a region on an enzyme that binds to a protein or other substance during a reaction.

amino acid

The building blocks that make up a protein molecule.

carbohydrate

Food belonging to the food group consisting of sugars, starch and cellulose.

covalent bond

A bond between atoms formed when atoms share electrons to achieve a full outer shell of electrons.

denatured

The structure and function is altered. This can be caused by heat, altered pH or by chemical agents.

emulsion

Cloudy mixture formed between a lipid and water.

TERM

enzyme

DEFINITION

A protein which catalyses or speeds up a chemical reaction.

fats

Naturally occurring compounds of carbon, hydrogen and oxygen. They are esters made from fatty acids and glycerol.

lipid

Fat or oils, composed of fatty acids and glycerol.

metabolism

All the chemical reactions in the cells of an organism, including respiration.

molecule

A collection of two or more atoms held together by chemical bonds.

oils

Natural substances produced from the reaction of glycerol with fatty acids.

pH

power of hydrogen. Scale of acidity or alkalinity. Below 7 is acidic, above 7 is alkaline.

protein

Organic compound made up of amino acid molecules. One of the three main food groups, they are needed by the body for cell growth and repair.

TERM

substrate

DEFINITION

A substance on which enzymes act.

optimum temperature

The temperature at which an enzyme is most active

optimum pH

the pH at which an enzyme is most active

Emulsion test

laboratory test for lipids using ethanol; a white emulsion indicates the presence of a lipid.