Science High School Reviewer | Grade 4 Science | Life Science | Kingdoms of Life | Lesson 5: Characteristics of Plants

5.1 Plant cells

All plants are made of cells. Plants may look
different, but they have many of the same kinds
of cells. The cells are organized into tissues, and
tissues are organized into organs. Each plant has
special parts that use the water and materials
that it absorbs from the soil. Some of the special
parts use the energy from sunlight to change
the water and materials into food for the plant.
Other parts transport the food to the cells in the
rest of the plant.

Plant Habitats
Plants live in many kinds of
habitats—from cold mountain
meadows to blistering hot
deserts. Plants have special
adaptations that help them
survive in their environment.
Some plants, like water lilies,
grow in the soil at the bottom
of ponds. The stems reach
up through the water, and
a flower blooms above the
surface. Large leaves float on
the water and trap sunlight
energy. You may know these
leaves as lily pads.

5.2 How plants make food

Sunlight and water are two things that
plants need to live, grow, and reproduce.
Plants also need carbon dioxide from
the air and mineral nutrients
from the soil.

Photosynthesis
Unlike animals, plants make their
own food. The food they make is sugar.
The process of making the sugar is called
photosynthesis. In photosynthesis,
plants use carbon dioxide that their
leaves absorb from the air and water
that their roots absorb from the soil.
The water and the nutrients it carries
travel through tubes in the stem to the
leaves. The plants use sunlight energy
to change these ingredients into food.
Oxygen and water, the waste products of
photosynthesis, pass into the air through
openings in the leaves. Tubes in the stem
carry sugar to other parts of the plant.
The stems, roots, and leaves all store
extra sugar.

Chloroplasts
Photosynthesis takes place in the chloroplasts of
leaf cells. When you look at chloroplasts through
a microscope, you see stacks of dark green disks
connected by threadlike materials. Chloroplasts
contain chlorophyll. Chloro is a Greek word for
“green.” Chlorophyll is the substance in plants that
makes them green. But chlorophyll does a lot more
than make plants green. It captures energy from
sunlight. Plants use this energy to change water,
carbon dioxide gas, and mineral nutrients from the
soil into oxygen, sugar, and other foods.

Cross-section of a leaf