Answer:
The correct answer is - decreased population size at all levels.
Explanation:
A decrease in the productivity of producers of an ecosystem will lead to a decrease in all other organisms of the ecosystem including top-level consumers to the bottom-level producers due to the fact that producers provide energy and food to primary consumers.
It is because they are the only organisms that convert the sunlight to usable energy and food that transfer from one trophic level to other, so if the population of producers or their productivity will decrease then there will be decreased population size at all levels.
Answer;
Evolution
Mutations such as polyploidy and crossing over provide the genetic basis for evolution.
Explanation;
Evolution is the change in the characteristics or traits of a species over several generations and relies on the process of natural selection.
It occurs when some individuals or some alleles (alternative form of gene) reproduce themselves more than others,increasing their prevalence in subsequent generation.
Polypoidy and crossover brings about mutations that cause changes in characteristics and traits over time resulting to evolution.
Jugular vein, cephalic vein, and the saphenous vein.
The chromosomes become visible when they hit the mitosis stage in the cell cycle.
