Teacher Geeks - 7th grade Science | 7th grade science



Reproduction in Plants

We looked at how seeds germinate, but not all plants reproduce the same.

Spores

Simple reproduction is found in lower forms of plant life. Simple plants, like mold, reproduce by spores. Each spore is a tiny cell with a tough cell wall. The plants produce millions of spores which are released into the air by the parent plant. Those spores may stay alive for years without developing. When the spore lands where the conditions are right, it will start to grow.

Cuttings

Some higher plants can reproduce from a cutting. A cutting is part of a plant that has been removed. Shoots with leaves attached are usually used. New roots and leaves will grow from the cutting. The shoot is cut at an angle. A growth promoter may be used to help with the growth of the roots. A cutting will grow into a new plant.

Materials: Swedish Ivy, plastic cup, scissors, naturalist’s notebook, pencil

What to do:

1. Label the cup with your table name and period.

2. Use your scissors to cut off the last 3 inches of one of the stems.

3. Fill the cup half full of water and put the end of the stem in the water.

4. Draw a sketch in your journal.

5. Check the water supply each class and sketch a picture each time you notice a change. Include the date for each picture.

Runners

Plants, like strawberries, can reproduce by runners. Runners are special stems that grow along the top of the ground. The end of the stem forms a root system which will eventually develop into another strawberry plant. When the new plant is matured, the runner dies.

Buds

Potato plants have stems that grow underground. These stems store food. As the food collects, the stems begin to swell. The swollen parts are the potato. The potato then forms buds that will grow into new plants.

Rhizomes

The grass in your lawn reproduces by rhizomes. Rhizomes are underground stems that grow directly into new plants. They can often spread quickly.

Bulbs

Tulips and onions can reproduce from bulbs. A bulb contains an underground stem. Leaves are attached to the stem. These leaves contain much stored food. Bulbs are really part of the stem. The bulb produces new bulbs at its base. Each new bulb grows into a separate plant. Bulbs grow as the plant produces excess food.

Seed Plants

As we saw before, most plants reproduce from seeds. Even many of the plants that have runners, buds, rhizomes, and bulbs reproduce by seeds. The seeds are made in the flowers of each plant.

Most flowers have both male and female reproductive organs. The male organ is the stamen and it produces a powdery substance which is the sperm called pollen. The female organ is the pistil. At the base of the pistil is a small opening called the ovary, and inside the ovary are the ovules, or eggs.

Though flowers all have the same parts, they may look different. When a flower matures, the pollen grains loosen from the stamen. Some grains are blown away by the wind. Some become attached to birds and insects. When pollen grains land on another flower of the same kind they attach to the sticky part of the pistil. Reproduction is about to begin. The pollen grain sprouts a long tube which grows down the pistil into the ovary. A special sperm cell will move down the tube into the ovary. It attaches to one of the ovules. This process is called fertilization.

Watch the video on pollination and answer the following questions.

1. Pollen from the ______________ of one flower must be carried to the _________________ of another flower.

2. What helps pollinate plants?

a. _______________ b. _______________ c. _______________

d. _______________ e. _______________ f. _______________

3. What adaptations have flowers made to attract insects to them?

______________________________________________________

4. What is the relationship called that plants have with the insects that pollinate them? _____________________________

Materials: flower, naturalist’s notebook, pencil, hand lens

What to do:

1. Go outside and find a flower.

2. Sit down and carefully observe the flower with your hand lens.

3. Sketch a picture of the plant and the flower and label all the parts of the plant and the flower. Describe the parts of the flower only.

Name: _______________________Period: ____Date: ____________

EXIT TICKET – Reproduction in Plants

1. What does pollen have in common with human sperm cells?

A. they are both male sex cells B. they are both female sex cells

C. they are both carried by insects D. they are both types of seeds.

2. What is another name for a fertilized ovule/

A. A pistol B. A stamen

C. An anther D. A seed

3. How does the pollination of most trees and grasses differ from the pollination of flowers?

A. Trees and grasses self-pollinate; flowers must get pollen from other flowers.

B. Trees and grasses pollinate in the springtime; flowers pollinate in the fall.

C. Trees and grasses are often pollinated by the wind; flowers are often pollinated by insects

D. Trees and grasses have large, heavy grains of pollen; flowers have small, fine grains of pollen

4. Honeybees and flowers are linked in a mutually beneficial relationship. What is a mutually beneficial relationship?

A. a relationship in which one participant benefits but the other does not

B. a relationship where neither participant benefits

C. a relationship in which one participant benefits but the other is harmed

D. a relationship in which both participants benefit

Name: _______________________Period: ____Date: ____________

EXIT TICKET – Reproduction in Plants

1. What does pollen have in common with human sperm cells?

A. they are both male sex cells B. they are both female sex cells

C. they are both carried by insects D. they are both types of seeds.

2. What is another name for a fertilized ovule/

A. A pistol B. A stamen

C. An anther D. A seed

3. How does the pollination of most trees and grasses differ from the pollination of flowers?

A. Trees and grasses self-pollinate; flowers must get pollen from other flowers.

B. Trees and grasses pollinate in the springtime; flowers pollinate in the fall.

C. Trees and grasses are often pollinated by the wind; flowers are often pollinated by insects

D. Trees and grasses have large, heavy grains of pollen; flowers have small, fine grains of pollen

4. Honeybees and flowers are linked in a mutually beneficial relationship. What is a mutually beneficial relationship?

A. a relationship in which one participant benefits but the other does not

B. a relationship where neither participant benefits

C. a relationship in which one participant benefits but the other is harmed

D. a relationship in which both participants benefit

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