Cambridge (CIE) O Level Biology: Photosynthesis

These vocabulary flashcards cover the process of photosynthesis, including equations, raw materials, carbohydrate storage, experimental procedures for starch testing, and the effects of limiting factors.

Photosynthesis

The process by which plants manufacture carbohydrates from raw materials using energy from light.

Chlorophyll

A green pigment found inside plant cell chloroplasts that absorbs light energy and transfers it into stored chemical energy in the bonds of glucose molecules.

Raw Materials

The substances required for photosynthesis, specifically carbon dioxide and water; light energy is required for the reaction but is not considered a substance/raw material.

Photosynthesis (Word Equation)

Carbon dioxide + water $\rightarrow$ glucose + oxygen (in the presence of light and chlorophyll).

Photosynthesis (Balanced Chemical Equation)

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$$

Starch

An energy store for plant cells made from glucose; its presence in leaves is a reliable indicator that photosynthesis has occurred because glucose is used or converted quickly.

Cellulose

A carbohydrate produced by plants to build cell walls.

Sucrose

A carbohydrate converted from glucose for transport in the phloem.

Iodine Solution

A chemical used to test for starch; it turns blue-black in the presence of starch and remains orange-brown if no starch is present.

Ethanol (in starch testing)

A flammable liquid used in a boiling tube to remove chlorophyll from a leaf so that iodine colour changes can be seen clearly.

Variegated leaf

A leaf that is partially green and partially white, used to demonstrate that chlorophyll is needed for photosynthesis.

Sodium hydroxide

A chemical used in photosynthesis experiments to absorb carbon dioxide from the surrounding air.

Limiting factor

An environmental factor that limits the rate of a reaction when it is in shortest supply.

Denaturation

The process occurring at extreme temperatures where the specific shape essential to enzyme function is lost as chemical bonds break, causing reaction rates to decrease.

Pondweed (Elodea or Cabomba)

Aquatic plants used to investigate photosynthetic rates by measuring the volume of oxygen produced or counting bubbles released per minute.

Sodium hydrogen carbonate

A substance dissolved in water to investigate the effect of varying carbon dioxide concentrations on the rate of photosynthesis.

Hydrogencarbonate indicator

A pH indicator used to show carbon dioxide concentration; it turns yellow at the highest concentrations and purple at the lowest concentrations.

Indicator Color: Yellow

In hydrogencarbonate indicator, this represents the highest concentration of carbon dioxide, which occurs when respiration rate is faster than photosynthesis rate.

Indicator Color: Purple

In hydrogencarbonate indicator, this represents the lowest concentration of carbon dioxide, which occurs when photosynthesis rate is faster than respiration rate.

Indicator Color: Red

In hydrogencarbonate indicator, this represents the atmospheric level of carbon dioxide.