Biology

Animal Cells:

An animal cell's main features would include:

• Nucleus -This includes DNA and also controls all the activities of the cell.
• Cytoplasm - This is a liquid gel which most of the chemical reactions for life take place.
• Cell Membrane - Which controlss the passage of substances in and out of the cell.
• Mitrochondria- Structure in the cytoplasm where oxygen is used and most of the energy is released during respiration
• Ribosomes - Where Protein synthesis takes place. All protein needed in the cell are made here.

Plant Cells:

A Plant cell includes the features of a animal cell but also includes:

• Cell Wall - Made celluose which stregthns the cell and gives it support
• Chloropast- Found in green parts of the plants, they are green because they contain the green substance chlorophyll which gives the plant its colour. They absorb light energy to make food by photosynthesis.
• Pernament Vacoule- (a space in the cytoplasm filled with cell sap), which is important for keeping the cells rigid to support the plant.

Enzymes control the chemical reactions inside cells.

Some specialised cells are: Fat Cell , Cone cell from human eye, Root hair Cell and Sperm Cells. A brief description and adaptations of these:

• Fat Cell - These are storage cells, if you eat more food than you need these will fill up. There are 3 adaptations and these are :They are very little normal cytoplasm so they have plenty of room for a large amount. There is very little mitochondria as they don't need a lot of energy. They can expand.
• Cone Cell from human eye - They are light sensitive layer of your eye. They make it possible to see colour. The outer segment is filled with a special chemical know as visual pigment. This changes chemically in coloured light.
• Root Hair Cell - These enable plants to take in the water which they need. The root hairs themselves, which increase the surface area to move into the cell. A large permanent vacuole, which affects the movement of water from the soil across the root hair cell.
• Sperm Cells are usually released a long away from the egg are going to fertilise. They have long tails with muscle-like proteins so they can swim towards the egg, The middle section is full of mitochondria which gives it energy to move. A large nucleus to pass the genetic information on. Finally the acrosomes which stores digestive enzymes for breaking down the outer layers of the egg

Your cells need to take in substances such as oxygen and glucose. They also need to get rid of waste products and chemicals that are needed elsewhere in the body. Dissolved substances move in and out of your cells across the cell membrane. They can do this in 3 different ways - by diffusion, osmosis and active transport.

Diffusion - This is the net movement of particles from an area of high concentration to a low concentrated area. Diffusion happens when the particles of a gas or any substance solution , spreads out.

Diffusion takes place because of the random movement of the particles of a gas or a substance in the solution in WATER.

Rates of diffusion - If the particles move to a area that has a big difference of concentration it would happen quickly unlike if it was only a bit different.

The overall or net movement = particle moving in - particles moving out

Diffusion is passive - it takes place along a concentration gradient from high to low concentration and uses up no energy.

Questions on Chapter 1.1 - 1.4

• What are the main features found in all living cells?
• How do plant cells differ from animal cells?
• What are enzymes made of?
• What is an adaptation of a Fat cell and a Sperm Cell?
• Where does diffusion happen?
• Why do sharks find an injured fish or person so easily?
• What is meant by the net movement of particles?
• What is the difference between diffusion and osmosis?

Answers to question on following page:

• Nucleus - Acts as the brain of the Cell and also contains DNA
• Cytoplasm - where chemical reactions take place
• etc..... (these 3 for question 1)
• Plants make their own food compared to animal cells and also they have different features in their cells.
• Fat Cell - Can expand, plenty of room and have very little energy
• Sperm Cell - Long protein like tail, nucleus contains genetic information and middle section full of mitochondria which makes the sperm cell move.
• Diffusion happens in Water
• Because the particles spread out and they have a good scent.
• The overall movement (high concentration to low concentration)
• Diffusion particles spread gradually through water (like putting a drip of ink in water) it would gradually spread (concentration) and Osmosis also has particles that travel from high to low concentration although it specially refers to the movement of Water molecules. Both of these transports are examples of passive transport which requires no energy.