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Living Things - Plant Life Cycles and Photosynthesis

Grade 4IB

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

🔑Concepts

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The Plant Life Cycle consists of several stages: Seed, Germination, Seedling, Adult Plant, Pollination, and Seed Dispersal.

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Germination requires specific conditions to begin, including the presence of water (H2OH_2O), oxygen (O2O_2), and the correct temperature.

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Photosynthesis is the process by which green plants use sunlight to synthesize nutrients from carbon dioxide (CO2CO_2) and water (H2OH_2O).

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Chlorophyll is the green pigment found in chloroplasts that absorbs light energy required for the chemical reaction.

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During photosynthesis, plants release oxygen (O2O_2) as a byproduct, which is essential for the survival of aerobic organisms.

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Stomata are tiny pores on the leaf surface that allow for the exchange of gases like CO2CO_2 and O2O_2.

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Glucose (C6H12O6C_6H_{12}O_6) is the sugar produced during photosynthesis that provides energy for the plant's growth.

📐Formulae

Carbon Dioxide+Water+Light Energy→Glucose+Oxygen\text{Carbon Dioxide} + \text{Water} + \text{Light Energy} \rightarrow \text{Glucose} + \text{Oxygen}

6CO2+6H2O+energy→C6H12O6+6O26CO_2 + 6H_2O + \text{energy} \rightarrow C_6H_{12}O_6 + 6O_2

💡Examples

Problem 1:

Identify the gas that enters the plant through the stomata for photosynthesis and the gas that is released as a waste product.

Solution:

Inlet: CO2CO_2 (Carbon Dioxide); Outlet: O2O_2 (Oxygen).

Explanation:

Plants require carbon dioxide (CO2CO_2) from the atmosphere to create glucose and release oxygen (O2O_2) back into the air during the process.

Problem 2:

A student places a plant in a sealed glass jar with no sunlight. Why will the plant eventually stop producing C6H12O6C_6H_{12}O_6?

Solution:

The lack of light energy prevents the chemical reaction of photosynthesis.

Explanation:

Light energy is a necessary reactant in the equation 6CO2+6H2O→C6H12O6+6O26CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2. Without light, the chlorophyll cannot trigger the conversion of H2OH_2O and CO2CO_2 into chemical energy.

Problem 3:

Explain the role of water in the life cycle of a seed.

Solution:

Water (H2OH_2O) triggers germination.

Explanation:

When a seed absorbs H2OH_2O, it swells and breaks the seed coat, allowing the embryo to begin growing into a seedling.