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Cells and Living Things - Plant and Animal Cells

Grade 6IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Cells are the basic structural and functional units of all living organisms. All living things are either unicellular (one cell) or multicellular (many cells).

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Animal cells contain a nucleus (controls cell activities), cytoplasm (where chemical reactions occur), and a cell membrane (controls the movement of substances like O2O_2 and CO2CO_2 in and out).

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Plant cells contain all the components of animal cells plus a cell wall (made of cellulose for support), chloroplasts (for photosynthesis), and a large permanent vacuole (containing cell sap).

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The mitochondria are the 'powerhouses' of the cell where aerobic respiration occurs to produce energy: C6H12O6+6O2→6CO2+6H2O+energyC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}.

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Chloroplasts contain chlorophyll, which traps light energy for photosynthesis: 6CO2+6H2O→lightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2.

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Levels of organization in living things follow the hierarchy: Cells →\rightarrow Tissues →\rightarrow Organs →\rightarrow Organ Systems →\rightarrow Organism.

📐Formulae

Total Magnification=Magnification of Eyepiece×Magnification of Objective Lens\text{Total Magnification} = \text{Magnification of Eyepiece} \times \text{Magnification of Objective Lens}

Magnification(M)=Size of Image(I)Actual Size of Object(A)\text{Magnification} (M) = \frac{\text{Size of Image} (I)}{\text{Actual Size of Object} (A)}

Photosynthesis: 6CO2+6H2O→C6H12O6+6O2\text{Photosynthesis: } 6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2

Aerobic Respiration: C6H12O6+6O2→6CO2+6H2O\text{Aerobic Respiration: } C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O

💡Examples

Problem 1:

A student views a plant cell under a microscope. The eyepiece lens has a magnification of 10×10\times and the objective lens has a magnification of 40×40\times. What is the total magnification?

Solution:

400×400\times

Explanation:

The total magnification is calculated by multiplying the eyepiece magnification by the objective magnification: 10×40=40010 \times 40 = 400.

Problem 2:

If a biological drawing of a cell is 50 mm50\text{ mm} long and the actual size of the cell is 0.1 mm0.1\text{ mm}, calculate the magnification used for the drawing.

Solution:

500×500\times

Explanation:

Using the formula M=IAM = \frac{I}{A}, we divide the image size (50 mm50\text{ mm}) by the actual size (0.1 mm0.1\text{ mm}): 500.1=500\frac{50}{0.1} = 500.

Problem 3:

Identify the primary function of the vacuole in a plant cell and name the substance it contains.

Solution:

Storage and Support; Cell Sap.

Explanation:

The large permanent vacuole stores nutrients and waste products in a fluid called cell sap. It also helps maintain turgor pressure to keep the plant cell rigid.

Plant and Animal Cells - Revision Notes & Key Formulas | IGCSE Grade 6 Science