1.2 Specialised Cells, Tissues & Organs (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
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Define differentiation.
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Define differentiation.
The process by which cells develop the structure and characteristics needed to carry out their specific functions.
Define a specialised cell.
A cell that has developed particular features in order to perform a specific function.
Define a tissue.
A group of cells of similar structure working together to perform the same function.
Define an organ.
A structure made of different tissues working together to perform a specific function.
Define an organ system.
A group of organs with related functions working together to carry out a body function.
The levels of organisation, from smallest to largest, are: cell → tissue → organ → → organism.
The levels of organisation, from smallest to largest, are: cell → tissue → organ → organ system → organism.
Cells become specialised by a process called .
Cells become specialised by a process called differentiation.
How is a red blood cell adapted to its function?
Biconcave disc shape increases surface area for oxygen diffusion
Contains haemoglobin to carry oxygen
Has no nucleus, leaving more space for oxygen
How is a root hair cell adapted to absorb water and minerals?
The root hair increases surface area for absorption
Thin walls allow water to move through quickly
No chloroplasts, as there is no light underground
How is a sperm cell adapted for reproduction?
The acrosome contains digestive enzymes to penetrate the egg
The mid-piece has many mitochondria to release energy for tail movement
Contains a haploid nucleus with genetic material
How is a ciliated cell adapted to its function?
It has hair-like cilia on its surface that beat to move mucus and trapped particles along the airways.
How is a palisade mesophyll cell adapted for photosynthesis?
It is column-shaped to absorb maximum sunlight and contains many chloroplasts.
How is a xylem vessel adapted to transport water?
No end walls, giving a continuous column of water
Cells are dead and hollow with no organelles
Walls are thickened with lignin for support
True or False?
A tissue is made up of only one type of cell.
True.
A tissue is a group of cells of similar structure working together to perform the same function.
Define magnification.
How many times larger an image is than the actual (real) size of the specimen.
Magnification = image size ÷ .
Magnification = image size ÷ actual size.
How do you calculate the actual size of a specimen?
Actual size = image size ÷ magnification.
How do you calculate the image size of a specimen?
Image size = magnification × actual size.
True or False?
Magnification is measured in millimetres.
False.
Magnification has no units — it is written as, for example, ‘×10’ or ‘×5000’.
An image of a cell is 30 mm and it has been magnified ×3000. What is the actual size of the cell?
Actual size = image size ÷ magnification = 30 ÷ 3000 = 0.01 mm (10 µm).
A cell has an actual size of 0.05 mm and is magnified ×200. What is the image size?
Image size = magnification × actual size = 200 × 0.05 = 10 mm.
In exam questions you are usually expected to measure specimen sizes in , not centimetres.
In exam questions you are usually expected to measure specimen sizes in millimetres, not centimetres.
True or False?
To find the actual size, you multiply the image size by the magnification.
False.
You divide: actual size = image size ÷ magnification.
Define image size.
The measured size of the specimen as it appears in the magnified image or drawing.
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