unit 3 lesson 2 how do plants reproduce? · 10/3/2019 · unit 3 lesson 2 how do plants reproduce?...

Unit 3 Lesson 2 How Do Plants Reproduce?

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How Does a Garden Grow?


• The series of stages that a living thing goes through as it develops is called a life cycle. It is important to understand plant life cycles, because most of our food comes from plants.

• Most plants grow from seeds.


How Does a Garden Grow?


• First, a seed is placed in soil, so it can sprout. Next, the plant grows until it reaches maturity. A mature plant may grow flowers or cones. Then, these structures make more seeds.


Radish Life Cycle


• A radish goes through three stages during its life cycle.

• A radish seed contains an embryo of a plant. When a seed sprouts during a process called germination, an embryo begins to grow.


Radish Life Cycle


•As a plant continues to grow, it gets larger.

•When a plant grows to its full size, it reaches maturity. Mature plants can make seeds that can grow into new plants.


Flowers and Cones


• Flowers and cones are reproductive structures that make seeds. They produce sex cells.

• Sex cells are used during sexual reproduction.

• Male sex cells are called sperm, and female sex cells are called eggs.


Flowers and Cones


• Fertilization is the process of a sperm and an egg cell joining together.

• A fertilized egg grows into a new plant inside a seed.


Flowers and Cones


• In plants with cones, sperm are made in male cones, and eggs are made in female cones.


Flowers and Cones


• Most cone-bearing plants are trees, such as pines, spruces, and cycads.


Flowers and Cones



Flowers and Cones


• Most plants produce seeds in flowers.

• Petals are the outer parts of a flower.

• The male organ is the stamen. It consists of a thin stalk topped by a saclike anther, which produces pollen. These grains of pollen contain the sperm.

• The female organ is the pistil. Its rounded base contains eggs.

• Many flowers have both anthers and a pistil.


Flowers and Cones



The Power of Pollen


• Plants reproduce through pollination.

• Pollination is the process of pollen moving from a male plant part to a female plant part.

• Plants can be pollinated by 1. Wind

2. Flowing water

3. Pollinators, such as bees, birds, and butterflies.


Seeds on the Move


• Animals play a big role in moving plant seeds.

• Many animals eat fruit, which helps spread the seeds contained in the fruit.

• Other animals, such as squirrels, will find and bury seeds.


Seeds on the Move


• Seeds, such as burs, can also travel on an animal’s body.

• Wind and flowing water also move seeds.


Seeds on the Move



Other Ways Plants Grow


• A spore is a cell that can form into a new plant when the conditions are right.

• Some plants, such as mosses and ferns, grow from spores instead of seeds.




• Plants that grow from spores have two distinct forms in their life cycles. Spores are released when the structures that hold them break open. Wind carries the spore to a new spot. If the spot is good, the spore will grow into a plant.

3.2 Videos/Pollen release in conifer.mp4




• A fern, or frond, is one form of the plant. Spore clusters will grow on the underside of the fronds.

• If a spore lands in a place with good light and water, it begins to grow into a tiny, flat, heart-shaped structure.




• The heart-shaped structure is the other form of the plant. It produces eggs and sperm.

• If a sperm cell fertilizes an egg cell, a curled frond will begin to develop and push out of the ground.

• The new plant reaches maturity when it can reproduce.

unit 3 lesson 2 how do plants reproduce? · 10/3/2019 · unit 3 lesson 2 how do plants reproduce?...

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