#80 Aerobic and anaerobic respiration

Respiration releases energy from food.

There are 2 kinds of respiration: Aerobic and Anearobic. The main difference between them is that aerobic respiration involves oxygen and anaerobic respiration does not!

# 79 Respiration realeases energy from food

Respiration is the chemical reactions that break down  nutrient molecules in living cells to release energy.

07. Human Transport pdf

#78 Summary of human transport

Mammals have a double circulatory system, in which blood is moved through vessels by the regular contraction and relaxation of cardiac muscles in the wall or the heart.

# 77 Functions of lymphatic system

Credit: Adam

The lymphatic system is a collection of lymph vessels and glands. It has 3 main roles:

• Fluid balance: return tissue fluid to the blood

• Protection from infection: produce white blood cells lymphocytes

• Absorption of fats: transport digested fats from villi to blood stream

#76 Immune system - antibody production, tissue rejection & phagocytosis

The immune system is the body's defence against disease and foreign bodies, under the form of antibody production, tissue rejection and phagocytosis. 

#75 Blood clotting

When an injury causes a blood vessel wall to break, platelets are activated. They change shape from round to spiny, stick to the broken vessel wall and each other, and begin to plug the break. 

# 74 Blood cells - structure and functions

Blood consists of cells floating in plasma. 
Most of the cells are red blood cells. 
A much smaller number are white blood cells.

There are also fragments formed from special cells in the bone marrow, called platelets. 

# 73 Blood composition and Plasma

If blood is allowed to stand without clotting, it separates out into 4 components: plasma, red blood cells, white blood cells and platelets.

The plasma and red blood cells play an important role in the transportation of substances, around the body.

White blood cells and platelets are part of the body's immune system.

# 72 Arteries, veins and capillaries - structure and functions

There are 3 main kinds of blood vessels – arteries, veins and capillaries. 

• Arteries carry blood away from the heart. They divide again and again, and eventually form very tiny vessels called capillaries. 
• The capillaries gradually join up with one another to form large vessels called veins. 
• Veins carry blood towards the heart.

#71 Effect of exercise on heartbeat and causes of coronary heart disease

A heartbeat is a contraction. Each contraction squeezes blood to the lungs and body. The heart beats about 70 times a minute, more if you are younger, and the rate becomes lower the fitter you are.

# 70 Structure and function of the heart

The function of the heart is to pump blood around the body. The right side pumps blood to the lungs and the left side pumps blood to the rest of the body. 

# 69 Transport in humans - the circulatory system

The main transport system of human is the circulatory system, a system of tubes (blood vessels) with a pump (the heart) and valves to ensure one-way flow of blood.

Its functions:

• To transport nutrients and oxygen to the cells.
• To remove waste and carbon dioxide from the cells. 
• To provide for efficient gas exchange.

06. Plant Transport pdf

#68 Summary of plant transport

In plants, xylem vessels transport water and mineral ions from the roots upwards to the leaves. Phloem tubes transport sucrose and other organic nutrients, from the leaves where they are made to all parts of the plant. This is called translocation.

#67 Transport of materials from sources to sinks at different seasons

'Source' is the part of a plant where substances are produced (e.g. leaves for sucrose, amino acids) or enter the plant.

'Sink' refers to the part of the plant where the substrate can be stored (e.g. roots or stem for starch).

#66 Translocation of applied chemicals (pesticides) throughout the plant

People who grow crops for food sometimes need to use chemicals called pesticides. Pests such as insects that eat the crop plants, or fungi that grow on them, can greatly reduce the yield of the crop. Pesticides are use to kill the insects or fungi.

# 65 Translocation of organic foods in plants

Translocation is the movement of organic food such sucrose and amino  acids  in phloem; from regions of production to regions of storage OR regions of utilisation in respiration or growth.

#64 Adaptations of the leaf, stem and root to different environments

Plants which live in extreme environments have adaptations to control their transpiration rate. Most modifications are adaptations to very dry (arid) environments. 

Water plants have no problems of water shortage.  They do not need adaptations to conserve water as desert plants.  

# 63 Transpiration in plants and factors affecting transpiration rate

In the leaves, water molecules leave the xylem vessels and move from cell to cell. They move through the spongy mesophyll layer by osmosis along a concentration gradient. Water then evaporates into spaces behind the stomata and diffuses through the stomata into the surrounding air.

#62 Passage of water through root, stem and leaf

Water enters root hair cells by osmosis. This happens when the water potential in the soil surrounding the root is higher than in the cell à water diffuses from the soil into the root hair, down its concentration gradient.

# 61 Root hairs and water uptake by plants

Plants take in water from the soil, through their root hairs: 

At the very tip is a root cap. This is a layer of cells which protects the root as it grows through the soil. 

The rest of the root is covered by a layer of cells called the epidermis.

The root hairs are a little way up from the root tip. Each root hair is a long epidermal cell. Root hairs do not live for very long. As the root grows, they are replaced by new ones. 

#60 Distribution of Xylem and Phloem in roots, stems and leaves

Root

In the roots, xylem and phloem are in the centre to withstand stretching forces. 

#59 Transport in plants - functions of xylem and phloem

Plants have transport systems to move food, water and minerals around. These systems use continuous tubes called xylem and phloem:

- Xylem vessels carry water and minerals from the roots to the leaves.  

- Phloem tubes carry sugar & other organic nutrients made by plant from the leaves to the rest of the plant. 

05. Animal Nutrition pdf

#58 Summary of animal nutrition

A balanced diet contains suitable proportions of each group of nutrients – carbohydrates, fats, proteins, minerals, vitamins, water and fibre – and the correct amount of energy.

# 57 Assimilation and role of the liver

Assimilation is the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells.

# 56 Absorption, small intestine and significance of villi

Absorption is the movement of digested food molecules through the wall of the intestine into the blood or lymph.