An operculum covers and protects the gills.
Explanation:
An operculum is a flexible bony type of plate which protects the sensitive gills. When water is inhaled through the mouth it moves over the gills and is exhaled from below the operculum ( gill cover). gills remove oxygen that is present in the water and diffuse carbon dioxide from fish's body. Some fishes have spines which are located on the opiculum( gill cover) which acts as a defense mechanism to secure them from the predators.
They are all part of the digestive system, they all break down food, they all have enzymes
Answer N0 1)
Lights are left on overnight:
If lights are left on overnight, then the process of photosynthesis will also occur during the night time when the sun is not present. Hence, this method is beneficial.
Farmers can also add fertilizers to the soil:
The addition of fertilizers to the soil allows essential nutrients to be taken up by the plant which will enhance its photosynthetic activity.
Extra carbon dioxide can be pumped into the green house. This comes from the burning of fuel like paraffin which releases. Carbon dioxide as a by-product.
Plants convert carbon dioxide and water into oxygen and glucose during photosynthesis. Hence, this process can be somewhat beneficial.
Fossil fuels are burnt (expensive) to keep the green house nice and warm.
Burning of fossil fuels to keep the green house warm is not an efficient process because this will deplete the natural resources.
Answer No 2)
Plants are protected from unfavourable conditions in a green house. Conditions such as harsh temperatures or harsh wind or floods can completely destroy crop plants. Hence, plants can be grown in the green house where favorable conditions are maintained for their growth.
