Exam 39: Plant Responses to Internal and External Signals

Plant hormones produce their effects by ________. I. altering the expression of genes II. modifying the permeability of the plasma membrane III. modifying the structure of the nuclear envelope membrane

Upon exposure to blue light, plants not only begin to grow toward the light, but move their chloroplasts to the sunny side of each cell. The adaptive advantage of moving chloroplasts to the sunny side of each cell ________.

Suppose a plant had a photosynthetic pigment that absorbed far-red wavelengths of light. In which of the following environments could that plant thrive?

An individual plant was discovered that could not grow towards light. After some research, it was determined that the reason was a defective gene that did not allow for the level of cell elongation necessary for a phototropic response. This mutation greatly reduces the fitness of the individual plant. Which reason best describes the reason for the loss of fitness?

An eccentric millionaire botanist has offered a $25,000 scholarship to anyone who can successfully get a plant to grow through a vertical maze in complete darkness. The maze is not in a box; the maze is simply drawn on the wall, and the contestants must get their plant to grow in a pattern that matches the path through the maze. You need the money and feel confident that you can accomplish this task. Which of the following techniques will help you succeed?

How may a plant respond to severe heat stress?

Which of the following mechanisms is in the correct sequence of steps (I-IV as listed below) that takes place during the formation of de-etiolation (greening) response proteins in plants? I. Detection of light signal II. Activation of phytochrome III. Activation of specific protein kinase1 IV. Formation of de-etiolation response protein

As cytokinins are primarily produced in roots, what route would they travel to influence lateral shoot formation in a recently topped tree?

Auxins in plants are known to affect which of the following processes? I. gravitropism of shoots II. maintenance of seed dormancy III. phototropism of shoots IV. inhibition of lateral buds V. apical dominance

When an arborist prunes a limb off a valuable tree, he or she may paint the cut surface. The primary purpose of the paint is to ________.

Mammalian eyes sense light because the photoreceptor cells have molecules called "opsins", which change structure when exposed to light. Which of the following plant molecules would be analogous to mammalian opsins in their light-sensing ability?

Which of the following mechanisms is the correct sequence of events that takes place during the plant responses to internal and external signals?

Generalised defence responses in organs distant from the infection site are called ________.

If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering?

Charles and Francis Darwin discovered that

Vines in tropical rain forests must grow toward large trees before being able to grow toward the sun. To reach a large tree, the most useful kind of growth movement for a tropical vine presumably would be ________.

What are the primary sites of ethylene production in high concentrations in plants?

Which of the following can function in signal transduction in plants? I. calcium ions II. nonrandom mutations III. receptor proteins IV. autochrome V. secondary messengers

Which of the following environmental factors can be sensed by plants? I. gravity II. pathogens III. wind IV. light

The biological clock controlling circadian rhythms must ultimately ________.