17. Which of the following actions by humans adds the greatest amount of carbon dioxide to
the atmosphere?
A cultivating new breeds of plants
C burning coal for electricity
B using solar powered calculators
D planting grass in neighborhoods

C. Burning coal for electricity.

Explanation:

When fuels like wood, coal petroleum and natural gas are burnt, the carbon in them is oxidized to carbon dioxide which returns to the atmosphere. Coal, petroleum and natural gases are known as fossil fuels. Coal comes from the partly decayed remains of ancient plants that became buried millions of years ago and were subjected to great pressure. As these fossil fuels take time millions of years to form, the carbon in them tends to recycle very slowly. In as much as they take time to form, they are been used up rapidly.

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.