Cottonwood, aspen, and willow trees have drab- coloured flowers with no petals that appear before the tree's leaves are out in the spring; they are dioecious. What does that indicate about these trees?
It is estimated that animal- or insect- pollinated plants produce 1000 pollen grains for each ovule; wind- pollinated plants produce 1,000,000 pollen grains for each ovule. What does that indicate about pollination systems?
A summer occupation in the Corn Belt states is de- tasseling the corn: removing unwanted male flowers so that female flowers on the same plant are pollinated by the desired pollen for the hybrid corn. What does this tell you about corn?
The sperm and egg each contribute 50% of the nuclear genetic material to the zygote that becomes the embryo and the new plant. Mitochondria and plastids that become chloroplasts are passed primarily from the female parent. What feature of the male or female gametophytes accounts for this?
A population of flowers varies from deep blue to nearly white. Bees are active during the day and prefer colour. Moths are active at night, when colours are not very visible and white is more conspicuous. Design a scenario in which the blue and white flowers form two species where there once was one species. You must end with a conclusion that the two new species cannot interbreed a definition of a species).