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Animal Cells

Animal cells are held together with a thin cell membrane. The cell contains smaller parts called organelles. These include the nucleus, mitochondria and ribosomes. This is all surrounded by a watery substance called cytoplasm. With out the nucleus the cell would die becasue it contains the DNA. The mitochondria use glucose in respiration to release energy for the cell. Ribosomes synthesis proteins from simpler compounds called amino acids. Protiens are used the repair parts of a cell or for new cells. There are also specialised cells which are designed to do their job with ease. An example of a sepicialsied cell is a sperm cell, they have a high number of mitochondria near the tail so they have lots of energy to get to the egg. It also has enzyme by it's head so that is can get into the egg.

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Plant cells

Plant cells have a cell wall as well as a membrane this makes them stronger so that they can surport themsevles becasue they have no internal bone structure. They have everything that an animal cell has but it also has a vacuole with cell sap in them this also makes it stronger. It has chlorplast this contains a green substance called chlorophyll. Chlorophyll is involed in photosynthesis it absorbs the sun's light. An example of a specialised plant cell is the xylem vessels, these are made up of dead cells, arranged as long tubes of cell wall only, with no end walls between them. These transport water from the roots to the leaves.

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Bacteria and yeast

A bacteria cell has a cell wall and membrane. It doesn't have a nucleus the DNA just in the cytoplasm in the form of plasmids (these are portable pieces of DNA) and circular chromosomes made of DNA. The cytoplasm is where all the chemical reactions happens. The structure of a yeast cell is very similar to a plant cell apart from It doesn't have chloroplast.

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Diffusion of gas- The movement of perfume particles through the air is called diffusion. The closer you get to the flower the stronger the smell. The more particles there are the greater the concentration. Gas molecules diffuse through the air rapidly. Diffusion of liquid- When soluble substance is placed in water, the particles will start to diffuse. The particles move in random directions which causes them to bump into each other and into the water particles. When the particles are close together it is high concentration. The particles eventually spreads out to become equal through out the water particles. Diffusion through cell membrane- All plant and animal cells have a membrane. This has tiny holes which means small particles can pass by diffusion. The membrane is partially permeable. The net movement is from high concentration to low until the distribution is equal.

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Carbon Dioxide + water -Light_Energy- glucose+ oxygen The word "synthesis" means to combine or to join together to create something new. "Photo" means light. Photosynthesis is to combine carbon dioxide and water then with light energy it creates glucose and oxygen. The light energy is collected by the chlorophyll. An of the left over sugar (glucose) is stored as starch. This is because glucose is soluble and starch is not. You can tell if a plant has photosynthesised with the iodine test. If the leave stains blue -black it is producing starch if it stains brown there is no strach present.

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Limiting factors

The limiting factors are what affect the rate of photosynthesis. There are three limiting factors which are temperature, light intensity and carbon dioxide. When investigating the factors separately you'll find that as you increase a factor the rate of photosynthesis inceasers as well. However after a point it stops increases. This is because another factor is affecting the rate of photosynthesis.

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Uses of glucose produced in photosynthesis

We get our energy from foods that store carbohydrate. Potatoes and cereals are part of our staple diet. Both store a lot of carbohydrates. This isn't to help humans it is actuallly to help the plant to survive over the winter and to help them and new plants to grow in the spring. The energy is used for many differnt things in both plant and animal cells, such as new cell growth, or to repair of damaged cells. It can also be used in chemical recations o change some materials into others. More energy is used for the movement of materials inside the organism. Plants convert the glucose they don't use into starch. This helps it to survive through the winter and is easily converted back into glucose. Als starch doesn't reacted with other chemicals therefore means it will stay in that form.

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Enhancing photosynthesis

Farmers enhance photosynthesis by growing their plants in controled conditions such as greenhouses or polytunnels. By using these you can control light intensity, temperature and carbon dioxide concentrations (All the limiting factors). Also by using a greenhouse or a polytunnel it means that you can produce vegetables and fruits all year round when you mght not have been able to before. Such as strawberries and lettuce used to only be produce in the summer. Farmers will sometimes enhance light intensity in the winter with artifical light. However, in the summer farmers tend not to enhancelight intensity. Carbon dioxide concentration can be increased by burning fuels such as propane. The temperature is enhanced in the summer by boilers and radiators. In the summer the heat is enhanced because the greenhouse enhances the temperature by trapping the heat.

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Protien structure, shapes and functions

Our body is made up of 72% water and nearly 20% of the fat-free mass of our body is made up of protein. Hair skin and nails are made up of protein. Protein molecules, in the form of hemoglobin, carry oxygen in the blood and help with the clotting when you cut yourself. All proteins are made up of the same four elements carbon, hydrogen, oxygen and nitrogen. They are made up of long chains of smaller soluble molecules called amino acids. Twenty differnet types are found in living organisms. The long chain of them are know as polypeptide. The sequence of the chain is specific to every protein. These are repersented in different 3-D shapes. This shape is held by chemical bonds. On the surface there are often little depressions know as the binding site other molecules fit into these. Some protein structures are used for the muscel tissue. Hormones and antibodies are of proteins. The rate of chemical reactions that happen in animal and plant are increase by the action of proteins enzymes, which are catalysts. These are chemicals that speed up reactions.

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Characteristics of enzymes

Chemical reactions

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