Questions

An organism is a living thing, and there are two broad categories of organisms: those made up of only a single cell, and those made up of multiple cells.

Single-celled organisms means which contains only one cell are called unicellular organisms. 'Uni-' means 'one,' so the name 'unicellular' literally means 'one cell.'

Examples of Unicellular or Single celled organisms ::

Prokaryotic organisms like Bacteria,...

Some algae like green algae, euglena,...

Plants grow in size both in height and in grith. Enlargement  of cells already present cannot contribute much to the growth. Only addition of more and more cells could increase the size of the plant considerably.

Protists are eukaryotic organisms that cannot be classified as a plant, animal, or fungus. They are mostly unicellular, but some, like algae, are multicellular.

Kelp, or 'seaweed,' is a large multicellular protist that provides food, shelter, and oxygen for numerous underwater ecosystems.

True, Stress is a factor that contributes to heart disease risk.

More factors that contributes to heart disease risk are blood pressure, cholesterol, smoking, physical inactivity and overeating.

In the process of photosynthesis, plants need the sun's energy, water to make food for themselves in the form of ATP ( adenosine triphosphate ) , which is packages of energy.

Carbon :

coming into the plants ( or algae ) along with water make those ATP into a bigger molecule, which is know as glucose.

Formula: 6 CO2 + 6 H2O + Suns Energy -> glucose + oxygen

Photosynthesis has an affect on the carbon cycle because it reduces the amount of CO2 in the air and redirects it into sugars which feeds animals as well as humans.

Hence, Photosynthesis removes CO2 from the atmosphere and replaces it with O2.

Cast iron is a group of iron-carbon alloys with a carbon content greater than 2% and is a brittle material.

Its usefulness derives from its relatively low melting temperature.