Why was 1990 an important year regarding air quality? select two options.
the united states took first steps to keep the air clean.
cost-effective ways to reduce pollution were emphasized.
the united states created the environmental protection agency.
modifications and improvements were made to the clean air act.
funding was established under the clean air act to study air pollution.

answer: after carbon dioxide enters the leaf through stomata it moves into the mesophyll cells where photosynthesis occurs and glucose is constructed. respiration occurs when glucose (sugar produced during photosynthesis) combines with oxygen to produce useable cellular energy.

explanation:

that scientist would be robert hooke

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.