Organisation

Cells

Cells are the building blocks of all living organisms.

Specialised cells

As an organism develops, cells differentiate to from different

Mitochondria adaptations

Lots of mitochondria to provide energy for their journey, long tail to propel sperm to fertilise egg, nucleus contains a set of genetic material, acrosome contains enzymes to allow sperm to get through outer layer of the egg.

Muscle cell structure

Protein fibres that can contract, nucleus, many mitochondria for energy

Xylem cell

End to end with end walls that break down to from hollow tubes. The cell wall is strengthened by lignin

Phloem

End walls of cell allow sugars through but the support tubes and the cell is arranged with end to end into tubes with a companion cell

Root hair cell

lots of mitochondria for active transport of minerals and long projection to increase the surface area to absorb water and minerals

Tissue

A group of cells with a similar structure and function which all work together to do a job

Muscle/ glandular/ epithelial tissue

Contracts to produce movement/ produces substances such as enzymes and hormones/ covers organs

Organs

Groups of different tissues which all work together to perform a specific job

Stomach organ

Contains muscle tissue that contracts to churn contents, glandular tissue that produce digestive juices and epithelial tissue to cover the outside and inside of the stomach.

Organs

Organised into organ systems which are groups of organs working together to do a particular job

Digestive system

Is an organ system where several organs work together to digest and absorb food

organism

Lots of organ systems work together

Enzymes

Biological catalysts that speed up chemical reactions in living organisms

Enzymes properties

Space within the protein molecule called the active site, each enzyme catalyses a specific reaction and they work best at a specific temperature and pH called the optimum

Lock and key theory

Explains how enzymes work: the chemical that reacts (the substance) is the key and fits into the (active site) lock

denaturing

High temperature and extremes of pH make enzymes change shape, when it’s denatured it cannot work because the substrate doesn’t fit to the active site.

Enzymes in digestion

Produced in specialised cells in glands and in the lining of the gut

Enzymes in digestion stages

The enzymes pass out of the cells into the digestive system, they come into contact with food molecules, they catalyse the breakdown of large insoluble food molecules into smaller soluble molecules

Digestive enzymes

Protease, lipase and carbohydrate digest proteins, lipids and carbohydrates to produce smaller molecules that can be easily absorbed into the bloodstream.

Amylase

Produced in the salivary glans and pancreas. It’s a carbohydrase that breaks down starch into sugar

Protease

Produced in the stomach, pancreas and small intestine which breaks down proteins into amino acids.

Lipase

Produced in the pancreas and small intestine which breaks down lipids into fatty acids and glycerol.

Bile and digestion

Bike is a liquid made in the liver and stored in the gall bladder. It’s alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets, increasing the surface area for enzymes to act on. The alkaline conditions and large surface area increase the fat at which fat is broken down by lipase.

Blood

A tissue made by plasma. It has red and white blood cells and platelets.

Plasma

Transports various chemical substances around the body

Red blood cells

Contains haemoglobin which binds oxygen to transport it from the lungs to the tissues and cells which need it for respiration. No nucleus for more room for haemoglobin. Very small to fit through tiny capillaries and are shaped like biconcae discs, giving them a large surface area that oxygen can quickly diffuse across.

White blood cells

Help protect body against infection, can change shape so they can squeeze out blood vessels into the gissues or surrounding and engulf microorganisms.

Platelets

Fragments of cells which collect at wounds and trigger blood clotting

Blood Vessels

Blood passes around the body in blood vessels. Arteries, viens and capillaries

Arteries

Take blood away from the heart to organs and has thick walls made of elastic and muscle fibres, to resist the high pressure of the blood.

Veins

Take from the organs back to the heart and has thinner walls and valves to prevent backflow as the pressure is lower.

Capillaries

Joins arteries to veins and has narrow vessels with walls that are one cell thick to allow substances to be exchanged with the tissues

The Heart

Pumps blood around the body in a double circulatory system where blood passes through the heart twice on each circuit. It has four chambers: the left and right atrium which recieve blood from the veins and the left and right ventricles which pump the blood out into the arteries.

Blood entering the heart

Blood enters the heart through the atria which contracts and forces blood into the ventricles. The ventricles contract and force blood out of the heart. It has valves which stop the blood from following in incorrect directions. The natural resting heart rate is controlled by a group of cells in the right atrium which act as a pacemaker.

Gaseous exchange

The heart sends blood to the lungs via the pulmonary artery. Air obtained by breathing reaches the heart through the trachea which divides into two tubes. The bronchi- divides to form bronchioles- divide until they end in the tiny air sacs called alveoli, which there is mullions of that are adapted to be very efficient exchanging oxygen and carbon dioxide.

Alveoli

Have large moist surface area, very rich blood supply and are very close to the blood capillaries so the distance for gases to diffuse is small. The blood is then taken back to the heart through the pulmonary vein.

Health and Disease

Good health is the state of physical and mental of wellbeing.

Disease

It’s caused by part of the body not working properly

Communicable and non-communicable diseases

Diseases that can spread/ cannot be spread between organisms

Risk Factors

Aspects of a persons lifestyle, substances in the persons body or environment

Coronary Heart Disease

Layers of fatty material build up inside the coronary arteries and narrow them.

Coronary heart disease treatments

Stent: keep coronary arteries open. Statins: reduce blood cholesterol levels and slow down the rate at which fatty materials build up.

Cancer

Non-communicable. Have genetic risk factors which may run in families. Uncontrolled cell division and can form masses of cells called tumours. Benign- do not spread, contained by membrane. Malignant- spread in the blood to different parts of the body where they form secondary tumours.

Plant Tissues

Epidermis- covers the outer surface of the plant for protection.

Palisade mesothelioma- The main site of photosynthesis in the leaf.

Spongy mesophyll- Air spaces between the cells allow gases to diffuse through the leaf.

Xylem vessels- Transports water and minerals through the plant, from roots to leaves.

Phloem vessels- Transports dissolved food materials through the plant.

Meristem tissue- Found mainly at the tips of the roots and shoots.

Transpiration

The release of water through the stomata.

Factors that increase the rate of transpiration

Increase in temperature, more energy is transferred to the water to allow it to evaporate.

Faster air flow, blows away water vapour allowing more to evaporate.

Increased light intensity, causes stomata to open.

Increase in humidity, DECREASES the rate as the air contains more water vapour so the concentration gradient for diffusion is lower.

Stomata

Stomata closes at night because carbon dioxide is not needed for photosynthesis this reduces water loss. When there is lots of water, stomata opens so gases for photosynthesis are free to move in and out of stomata along with water from transpiration.

Translocation

Phloem tissue transports dissolved sugars from the leaves to the rest of the plant. The movement of food through the phloem tissue is called translocation.