AQA Biology paper 1

aerobic respiration

an exothermic reaction in which glucose is broken down using oxygen to produce carbon dioxide and water and release energy for the cells

anaerobic respiration

an exothermic reaction in which glucose is broken down in the absence of oxygen to produce lactic acid in animals and ethanol and carbon dioxide in plants and yeast. A small amount of energy is transferred for the cells

exothermic reaction

a reaction that transfers energy to the environment

glycogen

carbohydrate store in animals

lactic acid

the end product of anaerobic respiration in animal cells

oxygen debt

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

Mitochondria

Organelle that is the site of respiration

Responses to exercise

Heart rate increases, Breathing rate increases, glycogen in muscles is converted to glucose

endothermic reaction

a reaction that requires a transfer of energy from the environment

glucose

a simple sugar

limiting factors

limit the rate of a reaction, for example photosynthesis

photosynthesis

the process by which plants make food using carbon dioxide, water, and light

Reactants for photosynthesis

water and carbon dioxide

Products of photosynthesis

glucose and oxygen

Chloroplast

Site of photosynthesis

white blood cells

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

Sperm cells

It has a long tail and a streamlined head to help it swim. There are a lot of mitochondria in the cell to provide the energy needed. It also carries enzymes in its head to digest through the egg cell membrane.

light

energy source for photosynthesis

aorta

the artery that leaves the heart from the left ventricle and carries oxygenated blood to the body

arteries

blood vessels that carry blood away from the heart. They usually carry oxygenated blood and have a pulse

atria

the upper chambers of the heart

capillaries

the smallest blood vessels. They run between individual cells and have a wall that is only one cell thick

coronary arteries

the blood vessels that supply oxygenated blood to the heart muscle

double circulatory system

the circulation of blood from the heart to the lungs is separate from the circulation of blood from the heart to the rest of the body

epidermal

the name given to cells that make up the epidermis or outer layer of an organism

guard cells

surround the stomata in the leaves of plants and control their opening and closing

haemoglobin

the red pigment that carries oxygen around the body in the red blood cells

palisade mesophyll

the upper layer of the mesophyll tissue in plant leaves made up of closely packed cells that contain many chloroplasts for photosynthesis

phloem

the living transport tissue in plants that carries dissolved food (sugars) around the plant

plasma

the clear yellow-liquid part of the blood that carries dissolved substances and blood cells around the body

platelets

fragments of cells in the blood that play a vital role in the clotting mechanism of the blood

pulmonary artery

the large blood vessel that takes deoxygenated blood from the right ventricle of the heart to the lungs

pulmonary vein

the large blood vessel that carries oxygenated blood from the lungs back to the left atrium of the heart

red blood cells

biconcave cells that contain the red pigment haemoglobin and carry oxygen around the body in the blood

spongy mesophyll

the lower layer of mesophyll tissue in plant leaves that contains some chloroplasts and many large air spaces to give a big surface area for the exchange of gases

stent

a metal mesh placed in a blocked or partially blocked artery. They are used to open up the blood vessel by the inflation of a tiny balloon

translocation

the movement of sugars from the leaves to the rest of the plant through the phloem

transpiration

the loss of water vapour from the leaves of plants through the stomata when they are opened to allow gas exchange for photosynthesis. It involves evaporation from the surface of the cells and diffusion through the stomata

veins

blood vessels that carry blood away from the heart. They usually carry deoxygenated blood and have valves to prevent the backflow of blood

vena cava

the large vein that brings deoxygenated blood from the body into the heart

ventricles

chambers of the heart that contract to force blood out of the heart

white blood cells

blood cells involved in the immune system of the body. They engulf pathogens and make antibodies and antitoxins

xylem

the non-living transport tissue in plants that transports water from the roots to the leaves and shoots

active site

the site on an enzyme where the reactants bind

amino acids

building blocks of proteins

amylase

enzyme that speeds up the digestion of starch into sugars

bile

neutralises stomach acid to give a high pH for the enzymes from the pancreas and small intestine to work well. It is not an enzyme

carbohydrases

enzymes that speed up the breakdown of carbohydrates into simple sugars

carbohydrates

molecules that contain only carbon, hydrogen, and oxygen. They provide the energy for the metabolism and are found in foods such as rice, potatoes, and bread

denatured

the breakdown of the molecular structure of a protein so it no longer functions

differentiate

the process where cells become specialised for a particular function

digestive system

organ system where food is digested and absorbed

enzymes

biological catalysts, usually proteins

fatty acids

part of the structure of a lipid molecule

glycerol

part of the structure of a lipid molecule

lipase

enzymes that speed up the breakdown of lipids into fatty acids and glycerol

lipids

include fats and oils and are found in foods such as butter, olive oil, and crisps. They are made of carbon, hydrogen and oxygen

organ

an aggregation (collection ) of different tissues working together to carry out specific functions

organ system

a group of organs that work together to carry out specific functions and form organisms

proteases

enzymes that speed up the breakdown of proteins into amino acids

proteins

molecules that contain carbon, hydrogen, oxygen, and nitrogen and are made of long chains of amino acids. They are used for building the cells and tissues of the body and to form enzymes

simple sugars

small carbohydrate units, for example glucose

tissue

a group of specialised cells with a similar structure and function

adult stem cells

stem cells that are found in adults that can differentiate and form a limited number of cells

cell cycle

the three-stage process of cell division in a body cell that involves mitosis and results in the formation of two identical daughter cells

cloning

the production of identical offspring by asexual reproduction

differentiate

the process where cells become specialised for a particular function

embryonic stem cells

stem cells from an early embryo that can differentiate to form the specialised cells of the body

mitosis

part of the cell cycle where one set of new chromosomes is pulled to each end of the cell forming two identical nuclei during cell division

stem cells

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

therapeutic cloning

a process where an embryo is produced that is genetically identical to the patient so the cells can then be used in medical treatments

How many chromosomes in the human genome?

23 pairs

Where are stem cells found in plants?

Meristems in roots and stems

benign tumours

growths of abnormal cells that are contained in one area, usually within a membrane, and do not invade other tissues

cancer

the common name for a malignant tumour, formed as a result of changes in cells that lead to uncontrolled growth and division

carcinogens

agents that cause cancer or significantly increase the risk of developing cancer

correlation

an apparent link or relationship between two factors

ionising radiation

has enough energy to cause ionisation in the materials it passes through, which in turn can make them biologically active and may result in mutation and cancer

malignant tumours

invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours. They are also known as cancers

tumour

a mass of abnormally growing cells that forms when the cells do not respond to the normal mechanisms that control growth and when control of the cell cycle is lost

clinical trials

test potential new drugs on healthy and patient volunteers

placebo

a medicine that does not contain the active drug being tested, used in clinical trials of new medicines

preclinical testing

is carried out on a potential new medicine in a laboratory using cells, tissues, and live animals

communicable disease

disease caused by pathogens that can be passed from one organism to another

microorganisms

organisms that are usually single-celled and can only be seen using a microscope . They include bacteria, fungi, viruses and protists

mutation

a change in the genetic material of an organism

non-communicable diseases

are not infectious and cannot be passed from one organism to another

pathogens

microorganisms that cause disease

sexually transmitted disease (STD)

transmitted from an infected person to an uninfected person by unprotected sexual contact

vaccine

dead or inactive pathogenic material used in vaccination to develop immunity to a disease in a healthy person

virus

pathogens that are much smaller than bacteria and can only reproduce inside living cells of other organisms

Muscle cells

These cells are long (so that they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction

Alveoli

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

Bronchi

two short branches located at the lower end of the trachea that carry air into the lungs.

gas exchange

process of taking in oxygen and releasing carbon dioxide

Root hair cells

Cells on the surface of plant roots which grow into long "hairs" that stick out into the soil. This gives the plant a big surface area for absorbing water and mineral ions from the soil.

Cellulose

a carbohydrate composed of many monomers.

Magnification

Image size/actual size

Bacteria

don't have a true nucleus instead they have a single circular strand of DNA that floats freely in the cytoplasm

bacteria

Don't have chloroplasts or mitochondria