6th grade Science Plants growth Photosynthesis

1. PLANTS AND THEIR
GROWTH
Plants are a major group of living things including familiar
organisms such as trees, flowers, herbs, ferns, and mosses.
About 350,000 species of plants, defined as seed plants, bryophytes,
ferns and fern allies, have been estimated to exist.
As of 2004, some 287,655 species had been identified, of which
258,650 are flowering and 15,000 bryophytes.
Plants are mostly autotrophs, organisms that obtain energy from
sunlight or organisms that make their own food.

2. WHY THEY ARE IMPORTANT ?
• Most plants carry out a process called photosynthesis, which occurs in the chloroplasts of
plants .It is a common misconception that most of the solid material in a plant is taken from
the soil, when in fact almost all of it is actually taken from the atmosphere.
• Through a process known as photosynthesis, plants use the energy in sunlight to convert
carbon dioxide from the atmosphere into simple sugars. These sugars are then used as
building blocks and form the main structural component of the plant .Plants rely on soil
primarily for water (in quantitative terms), but also obtain nitrogen, phosphorus and other
crucial elemental nutrients. For the majority of plants to grow successfully they also require
oxygen in the atmosphere (for respiration in the dark) and oxygen around their roots.

3. WHATS
PHOTOSYNTHESIS ?
Plants need food to respire, grow and
reproduce. Unlike animals, plants are
able to make their own food by the
process of photosynthesis.
Photosynthesis takes place in the part of
the plant cell containing chloroplasts ,
these are small structures that
contain chlorophyll.
For photosynthesis to take place, plants
need to take in carbon dioxide (from the
air), water (from the ground)
and light (usually from the sun).

4. PROCESS OF PHOTOSYNTHESIS
• During photosynthesis, molecules in leaves capture sunlight and energize electrons, which
are then stored in the covalent bonds of carbohydrate molecules. That energy within those
covalent bonds will be released when they are broken during cell respiration. How long
lasting and stable are those covalent bonds? The energy extracted today by the burning of
coal and petroleum products represents sunlight energy captured and stored by
photosynthesis almost 200 million years ago.
• Plants, algae, and a group of bacteria called cyanobacteria are the only organisms capable of
performing photosynthesis. Because they use light to manufacture their own food, they are
called photoautotrophs (“self-feeders using light”). Other organisms, such as animals, fungi,
and most other bacteria, are termed heterotrophs (“other feeders”) because they must rely
on the sugars produced by photosynthetic organisms for their energy needs. A third very
interesting group of bacteria synthesize sugars, not by using sunlight’s energy, but by
extracting energy from inorganic chemical compounds; hence, they are referred to as
chemoautotrophs.
•

5. CARNIVOUROUS PLANTS ?
• Carnivorous plants are plants that derive some or most of their nutrients (but not energy, which
they derive from photosynthesis) from trapping and consuming animals or protozoans,
typically insects and other arthropods. Carnivorous plants have adapted to grow in places where
the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs. Charles
Darwin wrote Insectivorous Plants, the first well-known treatise on carnivorous plants, in
1875.[4] Carnivorous plants can be found on all continents except Antarctica, as well as many
Pacific islands.[5]
• True carnivores is thought to have evolved independently nine times in five different orders of
flowering plants and is represented by more than a dozen genera. This classification includes at
least 583 species that attract, trap, and kill prey, absorbing the resulting available nutrients .This
number has increased by approximately 3 species per year since the year 2000 .Additionally, over
300 protocarnivorous plant species in several genera show some but not all of these
characteristics.

6. THANKS FOR WATCHING and
REMEMBER, SAVE PLANTS 