Question

Greenhouse crops such as tomatoes and bell pepper have higher yields. This is due to
A) $CO_2$ as a limiting factor to photosynthesis
B) Tomatoes and bell pepper are not $C_3$ plants
C) $CO_2$ enriched atmosphere that leads to higher yields.
D) Due to diffused light in the green house

Answer 1

Greenhouses are spaces built mainly out of glass such that light can enter in freely, but other climatic conditions like temperature and humidity can be regulated. This allows for specific plants to be grown under optimum conditions.

Complete answer:
There are several crops that grow really well in the environment of a greenhouse. These include lettuce, peppers, cucumber, spinach, and tomato. The word greenhouse has lent its name to the scientific concept the greenhouse effect. This effect is due to the increased percentage of gases like $CO_2$ and methane in the atmosphere, which trap more heat on the surface.

Option A says that $CO_2$ is a limiting factor. In this situation it does not apply as within the glass walls of the greenhouse, the amount of carbon dioxide in the air is at a higher concentration. Therefore option A is incorrect.

Tomatoes and bell peppers are $C_4$ plants. In $C_4$ plants, carbon dioxide is concentrated around the bundle sheath cells. However, as the concentration of this gas is already at optimum in the greenhouse, it doesn’t make a difference whether the plants are $C_3$ or $C_4$. Option B is incorrect.

The atmosphere is enriched with carbon dioxide in a greenhouse. This provides an optimal concentration of the gas for photosynthesis and related activities, along with maintaining a warmer temperature. Option C is the correct answer.

Light in the greenhouse enters freely through the glass walls and roof. It is not particularly diffuse as the glass is clear. Option D is incorrect.

Note: While greenhouses are regulated environments for the growing of crops, they have disadvantages like pest problems as the natural control for pests is not available in this artificial situation.