Cambridge IGCSE Biology: Photosynthesis

A set of vocabulary flashcards covering the basics of photosynthesis, the starch test, leaf anatomy, and mineral deficiencies based on the Cambridge IGCSE Biology curriculum.

Photosynthesis

The process by which plants make their own food using energy from sunlight, combining water and carbon dioxide into glucose and oxygen.

Chlorophyll

A green pigment found inside chloroplasts, mostly in the palisade cells of the leaf, that captures sunlight energy.

Glucose

A product of photosynthesis used to store energy in plants, often as starch or other carbohydrates.

Oxygen

A waste product of photosynthesis that is essential for respiration in plants and animals.

Photosynthesis Word Equation

$$\text{Water} + \text{Carbon Dioxide} \rightarrow \text{Glucose} + \text{Oxygen}$$

2.4 – 2.7 billion years ago

The time period when bacteria began carrying out photosynthesis and slowly releasing oxygen into the Earth's atmosphere.

20%

The approximate percentage of Earth's atmosphere that is composed of oxygen, nearly all of which was produced by photosynthesis.

Boiling in water

The first step in testing a leaf for starch, which involves heating the leaf for approximately $2\,\text{minutes}$ to soften it.

Ethanol

A substance used during leaf testing to remove the green chlorophyll from the leaf cells.

Iodine solution

A chemical used to test for starch; it turns blue-black if starch is present and remains brown or yellow if it is not.

Blue-black

The color result seen when iodine solution is added to a leaf where starch is present, proving photosynthesis has occurred.

Upper epidermis

The layer of the leaf that protects the cells inside and is transparent to let light through.

Waxy cuticle

A layer on the leaf surface that reduces water loss by evaporation.

Palisade layer

The layer of a leaf packed with chloroplasts where most photosynthesis happens.

Spongy layer

A leaf layer containing air spaces that let gases move through the leaf.

Vein

A structure in the leaf that carries water in and food out.

Stomata

Pores in the leaf that allow $CO_2$ to enter and $O_2$ and water vapour to exit.

Magnesium

A mineral needed by plants to make chlorophyll; deficiency causes leaves to turn yellow.

Chlorosis

The condition where leaves turn yellow due to a lack of chlorophyll, often caused by magnesium deficiency.

Nitrate

A mineral needed for protein production; deficiency leads to stunted plant growth and fewer new cells.

Modern Farming Tools

Technology used to spot mineral deficiencies, including GPS, satellite images, sensors, and computers.