Plant hormone questions, biology questions, about plant hormone regulation

The knowledge points to be clear here are: the photosensitive part of the germ sheath is the tip; The sites of auxin production and lateral transport are at the tip of the coleoplast.

For the namen, although there is unilateral light, due to the blocking effect of the mica sheet, auxin cannot be transported laterally, and the auxin content on the light side and the backlight side is the same, and the same is for downward transport, so the germ sheath appears to grow upright.

For B, although there is one-sided light, which causes auxin to be transported laterally at the tip, the mica sheet blocks the downward transport of auxin, so the germ sheath behaves as neither growing nor bending, and for C, although it is uniform light, due to the blocking effect of the right mica sheet, the right auxin cannot be transported downward, and the left auxin can be transported downward, so the left side of the coleoplasty grows fast and shows a bend to the right.

A because auxin (IAA) can not mica sheets, so the growth rate on both sides is the same, not curved, light only promotes IAA backlight distribution, but because the mica sheet is separated, so the left and right distribution is consistent.

Because there is a mica sheet on the right side, auxin can only be transported from the left, and as a result, the left side grows fast, so it will bend to the right.

The curved growth of plants is due to the uneven distribution of plant hormones, and the plant hormones in the nail cannot be transported laterally at the tip, so they cannot grow in bends.

C bends to the right for the same reason as in the nail, the plant hormone cannot penetrate the mica sheet, so that the left side has more auxin than the right side.

Choose D because only the carton rotates, which is equivalent to the light on the right side, the auxin distribution A is greater than B, and the A side grows fast and bends to the right;

Only the agar block of the coleoplasty rotates, which is equivalent to uniform light, and the auxin distribution a is equal to b, and grows upright;

The whole device rotates at the same time, which is equivalent to the light on the right side, and the auxin distribution A is greater than B, and the A side grows fast and bends to the right, so D is selected.

If you choose D, you can use the elimination method to directly see the option D. The first method of processing is "only the carton is turned."", so that the light received by the coleopleoplasty always comes from the right, so A absorbs more auxin than B, so the side of the coleoplasty with A grows faster than the side with B, so the first coleopleoplasty with the tip grows to the right. Therefore, only item D is met.

Choosing D, the first case and the third case are both leaning towards the end of B to receive light, auxin will want to move by the end of A, so in the second figure is bent to the right, in the second case Ab receives the same auxin, and the second figure grows upright.

Select D (note that the auxin in the whole apparatus agar block will not be transferred due to centripetal force and other forces).

Since the centrifugal force acts on the side of the stem and root to centrifugal force to have a high concentration of auxin, the root is more sensitive to auxin, and the result is that the stem grows to the right and the root grows to the left, understand?

Option A, the growth effect of auxin on plants shows duality, that is, low concentration promotes growth, high concentration inhibits growth, and in the process of promoting the effect from small to large and then small, there may be two concentrations that have the same promoting effect on growth; Plant hormones have a regulatory effect on plant growth and development, and are not directly involved in life activities. When fruit trees hang fruits, auxin solution of appropriate concentration is used to promote the increase of fruit cell volume. Treating the unpollinated pistils of tomatoes with an appropriate concentration of auxin solution yielded seedless tomatoes. The childless trait of tomato is not heritable because it is caused by environmental conditions (auxin), whereas the childless trait of triploid seedless watermelon is heritable and is caused by alterations in the genetic material.

Answer: Plant hormone is a class of compounds, plant hormones are very small in the plant body, plant hormones do not directly participate in intracellular metabolic activities, plant envy and shout hormones some promote plant growth, some inhibit growth, so option D is in line with the topic.