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Topic 2: Life Cycles

What is a cycle?

  • A cycle is a sequence of events that continuously goes on and repeats.

What are cycles in living things?

  • Cycles in living organisms are called life cycles.

(Quick Revision)

Organism = living things

  • A living thing is something that grows, reproduces, needs air, food and water, and responds to changes.

Why do living things reproduce?

  • For the continuity of their own kind. This ensures their own kind will not go extinct.

Examples of life cycles:

Egg → Young → Adult Seed → Seedling → Adult The life cycle of a plant

Life cycles have either 3 or 4 stages.Plant Reproduction

  • Plants go through 3 processes in order to reproduce.

    1. Germination

    2. Flowering

    3. Pollination

Germination

  • Takes place at seed stage.

  • Seeds need water, oxygen, warmth to germinate.

  • In order for seeds to develop into a young plant, germination has to first take place.

  • During the seed stage, a seed gets its food for survival from the mass of seed leaves.

Order of GerminationRoot

  1. Shoot

  2. Leaves

Flowering Plants: Seed

  • Seeds need water, oxygen, warmth to germinate.

  • In order for seeds to develop into a young plant, germination has to first take place.

  • During the seed stage, a seed gets its food for survival from the seed leaves.

Graph:

Over time, the seed leaves' mass decreases.

  • The food in it has been used up.

  • When the plant finally develops its own leaves, the seed leaves are no longer needed.

  • Over time, the seed leaves wither and drop off.

Flowering Plants: Seed

  • Flowering plants with seeds

Non-Flowering Plants: Spore

  • Also the little yellow dots on leaves

  • Spores are light and are dispersed by wind.

  • Spore bags are found underneath leaves.

Pollination

  • Only grown flowering plant with flowers is required for plant reproduction.

  • Can take place between 2 plants of same species or in one flower.

  • Pollination is the transfer of pollen grains from the anther to the stigma of the same or another flower of the same species

  • Pollen Grains

    • Male reproductive cell (in plants)

    Pollination MUST take place first in order for fertilization to take place after.