Chapter 35

Question 1

stems can be:

Answer 1

1. herbaceous, with soft tissues

2. woody, with extensive hard tissues of wood and bark

Question 2

three main functions of stems

Answer 2

1. support
2. internal transport
3. production

Question 3

stems of some species are modified for ___ reproduction

Answer 3

stems of some species are modified for asexual reproduction

Question 4

primary growth

Answer 4

occurs in all plants

increase length of a plant

occurs at apical meristems at root tips, shoots, and within buds of stems

Question 5

secondary growth

Answer 5

increase in the girth of a plant, adds wood and bark in woody plants

occurs at lateral meristems of stems and roots

Question 6

Herbaceous Eudicot Stems

Answer 6

Vascular bundles are arranged in a circle in cross section

Question 7

pith

Answer 7

storage of nutrients

Question 8

monocot stems

Answer 8

vascular bundles are scattered throughout the stem, each vascular bundle is enclosed in a bundle sheath of sclerenchyma cells

Question 9

monocot stems have no distinct areas of ___ and ___

Answer 9

monocot stems have no distinct areas of cortex and pith - ground tissue around the vascular tissues performs the functions of cortex and pith

Question 10

monocot stems have no ___ and no ___ growth

Answer 10

monocot stems have no meristems and no secondary growth

Question 11

water and minerals travel only ___ in xylem, whereas translocation of dissolved sugar may occur ___ or ___ in separate phloem cells

Answer 11

water and minerals travel only upward in xylem, whereas translocation of dissolved sugar may occur upward or downward in separate phloem cells

Question 12

transport of xylem ___ is the most rapid of any movement of materials in plants

Answer 12

transport of xylem sap is the most rapid of any movement of materials in plants

Question 13

water moves by

Answer 13

water potential

Question 14

water potential

Answer 14

the free energy of water: a measure of a cells’s ability to absorb water by osmosis

Question 15

The water potential of pure water is conventionally set at

Answer 15

0 megapascals

Question 16

when solutes dissolve in water, free energy

Answer 16

decreases because ions induce hydration

Question 17

water moves from a region of ___ water potential to a region of ___ water potential

Answer 17

water moves from a region of higher water potential to a region of lower water potential

Question 18

Water moves by osmosis from soil into roots because roots contain

Answer 18

more dissolved materials (have lower water potential)

Question 19

The Tension-Cohesion Model

Answer 19

water is pulled up the plant as a result of tension produced at the top of the plant

1. the atmosphere has extremely negative water potential
2. Tension is caused by the evaporative pull of transpiration - the evaporation of water vapor from the plant
3. Tension pulls water from leaves, where most transpiration occurs (through stomata), up through stems and roots

Question 20

water molecules are cohesive because of

Answer 20

hydrogen bonding

Question 21

adhesion of water to xylem walls is due to

Answer 21

hydrogen bonding and helps maintain an unbroken column of water

Question 22

Root pressure

Answer 22

pushes water up through xylem toward the top of the plant

water moves into roots by osmosis because of the difference in water potential between the soil and the root cell

Question 23

mineral ions that are actively absorbed from the ___ are pumped into the ___, decreasing its water potential

Answer 23

mineral ions that are actively absorbed from the soil are pumped into the xylem, decreasing its water potential

Question 24

sugar produced during photosynthesis is converted into

Answer 24

sucrose

Question 25

sucrose is translocated from a source to a ___

Answer 25

sink

Question 26

type of sinks for sucrose

Answer 26

1. roots
2. apical meristems
3. fruits
4. seeds

Question 27

Pressure-flow model

Answer 27

solutes move in phloem by means of a pressure gradient that exists between the source and the sink

Question 28

at the ___, sucrose is moved from leaf ___ cells into ___ cells, which load it into ___ tube elements of phloem by active transport

Answer 28

at the source, sucrose is moved from leaf mesophyll cells into companion cells, which load it into sieve tube elements of phloem by active transport

Question 29

A proton gradient drives ___ uptake through specific channels by cotransport of H+ back into ___ tube elements

Answer 29

A proton gradient drives sugar uptake through specific channels by cotransport of H+ back into sieve tube elements

Question 30

Water moves by osmosis from xylem cells into sieve tube, increasing

Answer 30

Water moves by osmosis from xylem cells into sieve tube, increasing turgor pressure there

Question 31

At the sink, sugar is unloaded from sieve tube elements, increasing ___ ___ in sieve tube elements at the sink

Answer 31

At the sink, sugar is unloaded from sieve tube elements, increasing water potential in sieve tube elements at the sink

Question 32

water moves out of sieve tubes by ___ and into surrounding cells, decreasing turgor pressure in sieve tubes at the sink

Answer 32

water moves out of sieve tubes by osmosis and into surrounding cells, decreasing turgor pressure in sieve tubes at the sink