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Life Processes and Living Things - Life cycles of flowering plants

Grade 5IGCSE

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

🔑Concepts

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The Life Cycle: The sequence of stages a plant goes through from seed to adult plant, including germination, growth, flowering, pollination, fertilization, and seed dispersal.

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Flower Structure: The male reproductive part is the Stamen (Anther and Filament). The female reproductive part is the Carpel or Pistil (Stigma, Style, and Ovary).

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Pollination: The process where pollen is transferred from the Anther to the Stigma. This can occur via wind or insects.

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Fertilization: Once pollen lands on the stigma, a pollen tube grows down to the ovary. The male gamete fuses with the ovule to form a zygote, which develops into a seed. Representation: Male Gamete+Female Gamete→ZygoteMale\ Gamete + Female\ Gamete \rightarrow Zygote.

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Germination: The stage where a seed starts to grow into a plantlet. It requires three specific conditions: Water (H2OH_2O), Oxygen (O2O_2), and Warmth (suitable temperature).

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Photosynthesis: Though seeds use stored energy initially, the growing plant eventually produces food using the formula: 6CO2+6H2O→lightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{light} C_6H_{12}O_6 + 6O_2.

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Seed Dispersal: Mechanisms to spread seeds away from the parent plant to reduce competition for light and nutrients. Methods include wind (e.g., dandelion), water (e.g., coconut), animals (e.g., burdock or fruit), and explosion (e.g., pea pods).

📐Formulae

6CO2+6H2O→light/chlorophyllC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{light/chlorophyll} C_6H_{12}O_6 + 6O_2

C6H12O6+6O2→6CO2+6H2O+Energy (Respiration)C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + Energy\ (Respiration)

Growth Rate=ΔHeightΔTimeGrowth\ Rate = \frac{\Delta Height}{\Delta Time}

💡Examples

Problem 1:

A student places seeds in a container with plenty of H2OH_2O and keeps them at a warm 25∘C25^{\circ}C, but removes all the air using a vacuum pump. Will the seeds germinate?

Solution:

No, the seeds will not germinate.

Explanation:

Germination requires Oxygen (O2O_2) for the process of aerobic respiration (C6H12O6+6O2→6CO2+6H2O+EnergyC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + Energy). Without O2O_2, the seed cannot release the energy stored in its food reserves to grow.

Problem 2:

Identify the part of the plant that becomes the fruit and the part that becomes the seed after fertilization.

Solution:

The Ovary becomes the fruit, and the Ovule becomes the seed.

Explanation:

After the pollen nucleus fuses with the ovule nucleus, the ovule develops a tough coat to become a seed. The surrounding ovary wall swells and ripens to become the fruit, which often aids in dispersal.

Life cycles of flowering plants - Revision Notes & Key Formulas | IGCSE Grade 5 Science