Exam 31: Plant Growth and Development

A) branch development
B) root development
C) fruit ripening
D) gravitropism

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A) an apical meristem.
B) a leaf meristem.
C) an axillary bud.
D) a lateral meristem.
E) either apical meristem or an axillary bud.

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A) changes in cell number but not cell dimension in the apical meristem.
B) changes in cell dimension but not cell number in the elongation zone.
C) both changes in cell number and cell dimension, roughly equally.
D) thickening of the cell walls in the zone of maturation.

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A) They increase the surface area of root-to-soil contact for water and nutrient uptake.
B) Similar to hairs on stems, they protect the root from herbivory by soil arthropods.
C) They exclude salts such as sodium from entering the root.
D) They store starch for remobilization to the shoot during flowering and seed set.

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A) residual meristem cells in the pith.
B) the cortex.
C) vascular bundle procambial cells and parenchyma.
D) totipotent cells that migrate from the apical meristem.

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A) once, in seed plants.
B) multiple times.
C) at the same time as primary growth.
D) independently in different groups of plants.
E) multiple times and independently in different groups of plants.

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A) When a shoot apical meristem (but not an axillary bud) converts to a floral meristem, further development of the whole plant ceases.
B) Axillary buds can only grow out to become new shoots once the shoot apical meristem has been converted into a floral meristem.
C) Shoot apical meristems can revert to vegetative meristem identity after having converted to a floral meristem and producing a flower, but axillary buds that give rise to flowers cannot.
D) In shoot apical meristems that develop into flowers, the arrangement of floral organs is the same as that of the leaves produced earlier, while the floral organs of flowers that develop from axillary buds are free to follow a different arrangement.
E) None of the answer options is correct.

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A) axillary position relative to root hairs, analogous to shoot branching from buds axillary to leaves.
B) pith, a source of stored carbohydrate for growth of the new root.
C) epidermis, which allows roots to initiate in response to local soil conditions.
D) pericycle, thereby maintaining continuous contact with the vascular system of the parent root.

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A) the total number of cells in the treatment group shoots would be smaller
B) the girth of cells in the elongation and mature zones would be larger in the control group
C) the length of cells in the elongation and mature zones would be larger in the control group
D) cellulose molecules would be more randomly oriented in mature cell walls in the treatment group
E) auxin levels and cell wall extensibility would be lower in the treatment group

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A) a leaf
B) a flower
C) a branch
D) a root
E) None of the answer options is correct.

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A) Absorption of red light causes phytochrome to shift from its active state to its inactive state.
B) Absorption of red light causes phytochrome to shift from its inactive state to its active state.
C) Absorption of far-red light causes phytochrome to shift from its active state to its inactive state.
D) Absorption of red light causes a seed to germinate.
E) Phytochrome is slowly shifted from its active state to an inactive state in the dark.

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A) root cap cells are damaged or become separated as elongation in the tissue produced by the RAM forces it through the soil.
B) the root cap must add cells to cover the additional surface area created by the growing root tip.
C) the root cap needs to recruit new cells form the RAM to develop lateral root hairs.
D) the population of root cap cells needs to be replenished from the RAM as older root cap cells differentiate into epidermal, cortex, and vascular tissues.

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A) stimulates fruit formation.
B) inhibits photosynthesis.
C) stimulates stem elongation.
D) maintains seed dormancy.
E) is overexpressed in semidwarf varieties of plants.

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A) The tree developed more apical shoot meristems during that time period.
B) The tree may have experienced a drought or had limited access to nutrients during that time period.
C) The tree developed more secondary xylem during that time period.
D) The tree had ample access to water and other resources during that time period.

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A) the shoot will die because stems cannot produce new root meristems.
B) auxin traveling down through the stem in the phloem will accumulate at the cut end and trigger the initiation of root meristem.
C) axillary buds near the cut end will take on root meristem identity due to the disruption of strigolactone transport, and, because root meristems are not repressed by apical dominance, they will begin to grow.
D) branches at the cut end will become positively gravitropic in response to the loss of an auxin sink in the root. Their apical meristems will take on root meristem identity once they contact the soil, due to ethylene accumulation.

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A) Vascular cambia produce new cells.
B) Vascular cambia allow plants to grow in diameter.
C) New cells produced by vascular cambia result in an increase in stem length.
D) Vascular cambia produce the substance we commonly call wood.
E) Vascular cambia are responsible for secondary growth.

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