Biology, Eighth Edition (Raven)

Chapter 42: Plant Reproduction

Pre Test

A phase change involves which of the following alterations in plant development? (p. 828)
A)Development of floral organs.
B)Switch from a juvenile to an adult growth aspect.
C)Release of pollen.
D)Two of the above.
E)All of the above.
You are presented with a plant taken from an equatorial forest and one that was grown in northern Canada. What predictions might you make about the signals which would initiate flowering for each? (p. 830)
A)The equatorial plant would require sudden high temperatures to induce phase change for flowering, while the Canadian plant would require cold temperatures.
B)The equatorial plant would be day neutral while the Canadian plant would respond more strongly to changes in day length.
C)The equatorial plant would be a long-day plant, while the Canadian plant would be a short-day plant.
D)The equatorial plant would be a short-day plant, while the Canadian plant would be a long-day plant.
E)There is no way to predict what factors might influence flowering in the plants.
What trends have been observed in the evolution of flower form? (p. 837)
A)Floral parts tend to become more distinct and with larger numbers.
B)There's been a reduction in the number of floral parts, but they have gradually become more radial.
C)Bilateral symmetry, with an increase in floral parts is seen in advanced plants.
D)Fusion and grouping of floral parts, with an increase in the whorls is seen.
E)Floral parts have become reduced and sometimes fused together, with a trend toward bilateral symmetry.
Why might a flower be at a disadvantage if it produces more than a certain quantity of nectar required by its pollinators? (p. 841)
A)The high amount of sugar in the nectar could deplete the plant's entire reserves after making only a few flowers.
B)The nectaries could dry out, creating sticky traps that would bind up the pollinators, preventing them from visiting other flowers.
C)Birds tend to get bored by visiting the same flower over and over, and so limiting the amount of nectar keeps each flower interesting enough to ensure it's visited by the same birds time and time again.
D)Smaller pollinators might gorge themselves on a single flower and quit feeding after a visit to only a single flower, defeating the purpose of pollination, which is to disperse gametes to different flowers.
E)Nectar contains a lot of water, so producing large amounts would dehydrate the plant and also cause it to bend down because it's too heavy.
What kind of environment favors asexual reproduction and why? (p. 845)
A)Harsh environments promote asexual reproduction because there's not much leeway in trying out new variations: if the plant establishes the vegetative phase it clearly has good enough genetics. Outcrossing would drain the plant of resources needed just for survival.
B)Environments that are changing rapidly most often have asexual species because it's important to get lots of progeny out there. Since most won't survive, sheer numbers are required to get a foot hold to ensure survival.
C)Cold environments are best for asexual reproduction because insects, which are required for pollination, don't do well in the cold. Thus, a method for reproduction that bypasses insects is required.
D)Wet environments promote asexual reproduction because by bypassing a seed stage (which are sexually derived), they can't dry out and become dormant. Moist environments favour plants that drop from the "parent" and keep on growing.
E)Areas with many mammals cause selection against seeds because of excessive feeding on energy-rich seeds. By not creating a propagule rich in starch or oil, the plant reduces herbivory of its next generation.
A botanist shows you a plant late in fall that has absolutely no secondary growth in its stem, but the botanist insists it's a perennial. How can this be true? (p. 847)
A)Some herbaceous varieties grow slowly but do not form vascular cambium. Thus, it's years old but has no secondary growth.
B)The root system is well-established and persists for years, although the shoots it puts up only serve for a single growing season.
C)Most plants are annuals, which are so-named because they grow according to a regular time table that can be predicted according to an annually repeated pattern.
D)Herbaceous plants break down their lignified secondary tissue each fall. You were shown a plant that has already recycled its secondary growth.
E)The botanist was lying or incompetent. You can't find a shoot in a perennial that has no secondary tissue unless it's less than a year old.
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