Photosynthesis is a vital process for plants, animals and humans, and the environment? give at least two examples of how plants, animals and humans, and the environment benefit from photosynthesis.

When photosynthesis occurs, carbon dioxide is consumed by the plant and oxygen is the by-product of the reaction. Oxygen is vital to survival since we need it to breathe. 

Photosynthesis is how plants make food for themselves. We get our food directly (we eat vegetables) and indirectly (herbivorous animals)  from plants. 

Photosynthesis produces food for plants
this requires carbon dioxide and water to react in the present of sunlight and also chlorophyll to produce glucose and oxygen
1.animals need the oxygen supplied for respiration
2.photosynthesis helps to balance the carbon dioxide content in air, it reduces the amount of carbon dioxide thereby reducing occurrence of global warming
3.also there are animals that depend on plants for their food ,herbivores,without photosynthesis the crop will die depriving the animal of its food supply

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .