Exam 4

Question 1

Vascular plants have roots and shoots that

grow from their tips (apices).

Answer 1

Root function –
• anchors the plant
• penetrates soil to absorb water and minerals
* Roots can exert huge forces as they grow.
* Roots are adaptation to living on land.

Question 2

Vascular plants have roots and shoots that

grow from their tips (apices).

Answer 2

Shoot function –
• stems are scaffold for positioning leaves
• leaves are main site of photosynthesis
• flowers, fruits, and seeds formed on shoot
* Repeating unit of vegetative shoot is: internode, node, leaf, and axillary bud (but NOT reproductive structures)

Question 3

Three types of tissues composing roots and

shoots:

Answer 3

1) dermal tissue = epidermis
2) ground tissue =storage, photosynthesis, secretion, forming fibers for support and protection
3) vascular tissue = conducts fluids and dissolved substances

Question 4

Meristems are specialized cells in the root and shoot apices and other parts of the plant

Answer 4

• These cells act like stem cells in animals;A meristem cell divides to give rise to a differentiating daughter cell and a cell that remains as a meristem cell.

Question 5

Apical meristems – involved with extension of roots and shoots

Answer 5

• located at tips of roots and stems
  * new cells are added at tips
  * primary tissues = tissues derived from apical meristems
  * primary plant body = extension of root and stem

Question 6

Apical meristems – involved with extension of roots and shoots

Answer 6

• root cap – protects delicate cells of root apical meristem; sloughed off and replaced as root grows through soil
  * leaf primordia = shelter tender growing shoot apical meristem from desiccation

Question 7

Apical meristem gives rise to three tissue

systems:

Answer 7

1) protoderm – forms epidermis
2) procambium – produces primary xylem (water transport) and primary phloem (nutrient transport)
3) ground meristem – differentiates into more ground tissue

Question 8

Intercalary meristems found in horsetails and corn. They are in the internodes and add to the length of the internodes.

Answer 8

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Question 9

Lateral meristems – involved with increase in root and shoot diameter known assecondary growth.

Answer 9

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Question 10

Lateral meristems form from ground tissue that is derived from apical meristems. (Monocots are the major exception.)

Answer 10

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Question 11

Secondary growth can increase girth in nonwoody plants, but the effects are most striking in woody plants.

Answer 11

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Question 12

Woody plants have two lateral meristems:

Answer 12

1) cork cambium – contributes to outer bark of tree
2) vascular cambium – located just beneath bark; produces secondary vascular tissue

	a) secondary xylem = main component of wood
	b) secondary phloem = close to outer surface of woody stem; remove bark of tree  damage to phloem  may eventually kill tree

Question 13

Secondary tissues = most of trunk, branches, and older roots of trees and shrubs

Answer 13

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Question 14

Secondary plant body = all the secondary tissues

Answer 14

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Question 15

Plant Tissues:

Answer 15

As previously mentioned above, there are three main categories of plant tissues. These are described as dermal, ground, and vascular tissues. Examples of each are described in more detail below.

Question 16

1) Dermal tissue:

Answer 16

• one cell layer thick in most plants
• forms outer protective covering of plant
• cuticle composed of fatty cutin to protect young, exposed parts of plant
• desert succulents may also have several layers of wax to curb water loss and help block UV radiation
• sometimes, dermal tissue forms tree bark
• examples include . . .
a) guard cells
• paired, sausage-shaped cells that flank a stoma (opening) on the leaves, stems, and fruits of plants
• contain chloroplasts, unlike other epidermal cells
• allow passage of oxygen and carbon dioxide and diffusion of water in vapor form
• many times, stomata are more numerous on underside of leaves (minimizes water loss), but water lilies are exception

Question 17

c) root hairs

Answer 17

• extensions of epidermal cells, but NOT a separate cell
• increase surface area to maximize water and mineral uptake

Question 18

2) Ground tissue:

Answer 18

a) parenchyma
• most common type of plant cell
• function is storage of food and water, photosynthesis, and secretion
• cells may live for many years (over 100 years old in some cacti)
• most of the cells in fruits such as apples are parenchyma
• photosynthetic parenchyma is called chlorenchyma – found in leaves and outer parts of herbaceous stems

Question 19

b) collenchyma

Answer 19

• example is celery “strings”
  * tough, but flexible cells support plant organs allowing them to bend without breaking
  * found in stems and leaf petioles
  * have living protoplasm just likeparenchyma and can live for many years

Question 20

c) sclerenchyma

Answer 20

• cells have tough, thick walls
  * mature cells don’t have living protoplasm
  * cells contain lignin that makescells walls more rigid
  * two forms of sclerenchyma –

            1) fibers forming long, slender strands; linen woven from sclerenchyma fibers of flax plant
            2) sclereids vary in shape and are often branched; gritty texture of a pear is from  groups of sclereids in soft  flesh of fruit

Question 21

3) Vascular tissue:

Answer 21

a) xylem = principal water-conducting tissue made up of vessels and tracheids

	  Water moves in an unbroken stream 		  through the xylem from roots  shoot leaves

Transpiration = diffusion of water vapor from a plant

Question 22

3) Vascular tissue:

Answer 22

b) phloem = principal food-conducting tissue in vascular plants; phloem composed of sieve cells and sieve tube members

Question 23

Roots: Anchoring and Absorption Structures

Answer 23

Roots adapted for growing underground and absorbing water and solutes.

Question 24

Roots have four regions:

Answer 24

1) root cap = protects the root and functions in perception of gravity
2) zone of cell division = contains apical meristem
3) zone of elongation = extends root through soil
4) zone of maturation = cells become differentiated

Question 25

Modified roots accomplish specialized functions.

Answer 25

1) taproots consist of single large root with smaller branching roots 2) fibrous root systems are made up of many small roots of similar size 3) adventitious roots are roots that arise from the stem or some place other than the root of the plant (See examples on p. 740 of Campbell text). Adventitious roots can function in support, stability, acquisition of oxygen, storage of water and food, or parasitism of a host plant.

Question 26

Stems: Support for Above-Ground Organs

Answer 26

Stems carry leaves and flowers and support | the plant’s weight.

Question 27

Leaves are attached to the stem at the | nodes. Leaf arrangements may be:

Answer 27

a) alternate b) opposite c) whorled

Question 28

Leaves are attached to the stem at the | nodes. Leaf arrangements may be:

Answer 28

but, most often the leaves are arranged spirally around the stem 137.5° apart. This angle relates to the golden mean, a mathematical ratio found in nature. It is possible that this may maximize the exposure of leaves to the sun.

Question 29

Internal stem structure:

Answer 29

Organization of vascular bundles is a major distinctive factor between monocots and eudicots (also known as dicots).

Question 30

Monocots: vascular bundles are scattered throughout the ground tissue of the stem

Answer 30

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Question 31

Monocots: vascular bundles are scattered throughout the ground tissue of the stem

Answer 31

See p. 750 for diagrams of this)

Question 32

Modified stems carry out vegetative propagation and store nutrients. Following are some examples. (See p. 741)

Answer 32

a) bulbs: swollen underground stem consisting of fleshy leaves attached to small knoblike stem with adventitious roots at base (onions, lilies, tulips) b) corms: sort of look like bulbs, but when cut, there are no fleshy leaves. Corms are stems with some brown, papery nonfunctional leaves on the outside and some adventitious roots. (crocus, gladiolus) c) rhizomes: horizontal stems that grow underground. Adventitious roots grow from the lower surface. (perennial grasses, ferns, bearded iris) d) runners and stolons: horizontal stems with long internodes that grow just above the surface of the ground (strawberries)

Question 33

Modified stems carry out vegetative propagation and store nutrients. Following are some examples. (See p. 741)

Answer 33

``` e) tubers: tips of rhizomes swell and become tubers. The “eye” of a potato is evidence of where a leaf formed when the tuber started to grow. The “eye” is and axillary bud and will grow into a new potato plant. ``` f) tendrils: twining stems that aid in climbing (grapes, English ivy); Tendrils of peas and pumpkins are modified leaves.

Question 34

Leaves: Photosynthetic Organs

Answer 34

``` • primary sites of photosynthesis • determinate structures (i.e. they stop growing at maturity) blade = main part of leaf petiole = stalk that attaches leaf to main stem of plant veins = vascular bundles made of xylem and phloem a) monocots have parallel leaf veins b) eudicots have netted or reticulate veins (See p. 748) ```

Question 35

Leaf anatomy: Most leaves have dorso- ventral symmetry resulting in more surface area for photosynthesis. (p. 741) Leaves: Photosynthetic Organs

Answer 35

simple leaves = blades are not divided compound leaves = blades divided into leaflets

Question 36

Leaf tissues:

Answer 36

a) epidermis with guard cells b) vascular tissue c) mesophyll (site of photosynthesis)

Question 37

Modified leaves include:

Answer 37

a) floral leaves (bracts): surround the true flowers (which can be quite small) and act as showy petals (poinsettia, dogwood) ``` b) spines: (NOT the same as thorns or prickles) Spines are modified leaves on cacti and some other plants. They reduce water loss and can deter predators. ```

Question 38

Modified leaves include:

Answer 38

c) reproductive leaves: little plantlets growing along margins that when separated can grow into a full-sized plant (Kalanchoe) ``` d) insectivorous leaves: trap insects to provide supplemental nutrition for plant. These plants often live in acid swamps that don’t provide all the nutrients the plant requires. (Venus fly trap, sundews, pitcher plants) ```

Question 39

Chapter 37: Soil and Plant Nutrition

Answer 39

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Question 40

Soils: The Substrates on Which Plants Depend

Answer 40

Components of topsoil: a) mineral particles (inorganic compounds) b) living organisms (They break down and recycle organic debris.) c) humus (partially decayed organic material)

Question 41

Going from the surface down, we would find:

Answer 41

1) leaf litter and plant life 2) topsoil 3) subsoil 4) bedrock

Question 42

Most roots are found in the topsoil. Topsoil is characterized by the relative amounts of sand, silt, and clay. Sand binds water and nutrients minimally while clay binds water and nutrients very tightly.

Answer 42

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Question 43

Role of soil charge in transport:

Answer 43

1) Soil particles tend to have negative charge. 2) Positive ions attracted to soil particles. 3) Negative ions stay in solution around roots. This creates a charge gradient that tends to “pull” positive ions out of the root cells. 4) Active transport is required to acquire and maintain K+ and other positive ions in the root.

Question 44

Water and air fill pores among soil particles. | A balance of air and water in the soil is essential for root growth.

Answer 44

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Question 45

Cultivation can result in soil loss and nutrient depletion.

Answer 45

``` . • Up to 50 billion tons of topsoil have been lost from fields in the U.S. in a single year. • Causes can be: - erosion - poor landscaping - poor farming practices - drought (“Dust Bowl” in 1930s) • Solutions to combat erosion: - mixing crops in a field - conservation tillage - no-till practices (not plowing under fall crop detritus) - also important to minimize runoff of fertilizers from farms, lawns, and gardens into waterways that result in algal blooms ```

Question 46

pH and salinity affect water and mineral availablilty.

Answer 46

• Acidic soils release aluminum from rocks. Aluminum is toxic to plants and may combine with other nutrients making them unavailable to plants. • Salty soils draw water out of plants causing them to lose turgor pressure.

Question 47

Plant Nutrients Plants require nine macronutrients and eight micronutrients. (Table 37.1, p. 791)

Answer 47

1) Macronutrients include – carbon, oxygen, hydrogen, nitrogen, potassium, calcium, magnesium, phosphorus, sulfur 2) Micronutrients include – chlorine, iron, manganese, boron, zinc, copper, nickel, molybdenum

Question 48

Food security is related to crop productivity | and nutrient levels.

Answer 48

• Some goals of plant breeding involve increasing nutrient levels in food crops while they are growing in the field.

Question 49

Food security

Answer 49

1) Bacteria living in close association with roots can provide nitrogen. Legumes have a symbiotic relationship with bacteria living in the nodules of their roots. 2) Mycorrhizae aid a large portion of terrestrial plants. More than 90% of plants have a symbiotic relationship with “fungus roots.” 3) Carnivorous plants trap and digest animals to extract additional nutrients. These plants usually live in acidic, nitrogen-poor environments. 4) Parasitic plants exploit resources of other plants. Some parasitic plants are photosynthetic while others are not. They tap into a host plant to obtain nutrients, including carbohydrates.

Question 50

Carbon-Nitrogen Balance and Global Change Elevated CO2 levels can alter photosynthesis and carbon levels in plants.

Answer 50

• An increase in CO2 results in an increase in photosynthesis. This, in turn, leads to an increase in biomass. The plant tissue produced has a higher proportion of carbon compared to nitrogen resulting in a shift toward more carbohydrate and less protein. • With less protein available in plants, herbivores must eat more plants to get the same amount of nutrients. (Greater plant loss to herbivory.)

Question 51

Elevated temperature can affect respiration and carbon levels in plants.

Answer 51

• The higher the temperature, the greater the rate of enzyme reactions. Plant respiration breaks down carbohydrates and could result in changes in plant nutrient balance.

Question 52

Phytoremediation – uses plants to remove toxic contaminants from soil or water.

Answer 52

• Poplar trees remove trichloroethylene from soil and convert it to carbon dioxide and chlorine compounds. • Some plants can remove small amounts of TNT (trinitrotoluene) in soil and degrade it. • Heavy metals can be successfully removed at lower costs. Contaminants accumulate in shoots of plants and then plants are removed.