《IGCSE BIOLOGY》Topic 2
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Topic 2 [Organisation of the Organism]
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Cells are the of life, as all living organisms are made out of cells. Cells exist in various and . There are smaller components called within a cell and each organelle performs a inside the cell or for the cell.
:
- Also known as the .
- It is (Only allows some substances to pass through).
- The cell membrane is made of two layers. It had a (Love water) and a (Hate water) . Two layers of the head and tail connected together (Note that the tails are pointing towards each other) are called the .
:
between the cell and its' external environment
: (Only present in plant cells and fungus)
- A rigid layer surrounding the of .
- In fungus, the cell was is made of .
:
- To provide support and protection for the cell
- To prevent the cell from bursting in a dilute solution
:
- Between the and the .
- Containing organelles, salts, dissolved gases, nutrients, enzymes, and other organic molecules.
:
- Gives shape to the cell (Especially for animal cells, who do not have cell wall).
- Supports and protects the cell organelles
- Provides a medium for all to occur.
:
- Bound by the .
- Containing .
**The nucleus contains . The chromosomes contain .**
:
- Controls all cell activities
:
- Small, dot-like organelles found in large numbers in .
Two types of Ribosomes:
1. Attached to the .
2. Occur in the .
:
- To all types of .
:
- A flat, sealed sac of .
- attached on its' surface.
- Present in .
:
- and made by the ribosomes.
**Present in large amounts in cells that make proteins, such as gut cells.**
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- A tubular sac of .
- Does not have ribosomes.
:
- and .
**Present in large amounts in cells that make lipids: e.g cells in the liver.**
: (Note that the plural of Mitochondrion is Mitochondria)
- Rod-shaped.
- Has an inner and outer membrane.
- 'The powerhouse of the cell'.
:
- Carry out (Refer to Topic 1 definition of respiration), which release in the form of .
- is a molecule that acts as a energy source/currency for the cell.
**Cells with high rates of metabolism have high numbers of mitochondria.**
: (Only present in plants)
- Containing , , or .
- Largest organelle in plant cells as they store water.
:
- For , , and .
: (Only present in plants)
- Have inner and outer membrane.
- Contain to trap energy from the sun.
:
- To carry out .
:
Animal Cells:
> Has NO cell walls, nucleus (in the middle of the cell), cytoplasm, NO chloroplast, NO vacuole, cell membrane.
> Stores food in the form of , which is made of a large number of glucose molecules binded together. Glycogen is stored in the .
Plant Cells:
> Has cell wall, nucleus (at the side of the cell), cytoplasm, chloroplast, vacuole, and cell membrane.
> Stores food in the form of , mostly in the .
:
:The basic structure and of a living organism.
: A group of with similar function working together to perform a .
:A structure made up of a group of working together to perform a .
: A group of with related functions, working together to perform .
: Different work together to make up one whole functional and complete multicellular organism.
By the process of .
- The cells become according to the functions they have to form.
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- All cells are made in the , and they call start out as , which are cells with no specific function.
- Stem cells and become .
- Layer of tiny hairs: '', which move and push from one place to another.
- The mucus transports and traps dust and microbes in the trachea when pushed by the cilia.
- Conduct , which convey messages (Stimulus).
- Electrical impulses travel along a long fibre called the .
- A provides insulation for the nerve cell.
- There are many connections () at each end of the nerve cell to keep passing on the electrical impulse.
- A shape.
- Transport from the lungs to tissues for .
- The cytoplasm of red blood cell contains , a red pigment that carries oxygen.
- Matured red blood cells have to make more space for , so more oxygen can be transported.
- Very to pass through narrow blood vessels.
- Egg Cell (Aka. ), the .
- It is fertilised by a sperm cell to form a .
- Sperm Cell, the .
- They have a tail (flagellum) for swimming.
- They have a high amount of mitochondria to provide energy to swim and penetrate the ovum.
- and from the soil.
- Has (root hairs) to increase for absorption.
- and up the plant.
- so water can pass freely.
- as many cells have joined together to form a continuos tube.
- Wall strengthened by , a waterproof substance.
- The hollow space in the vessel is called the .
- The cells are , , and .
: (Magnification)
Magnification = Size of illustration / Actual size
1 cm = 10 mm
1 mm = 1000 µm
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