botany exam

Describe the five types of tissues found in a root. What is the function of each?

• Epidermis - single layer on outer surface selectively allows in water and minerals

• Cortex - of nonspecialized parenchyma cells

commonly are storage cells

• Endodermis - separates cortex from vascular tissue (distinct, visible layer) reduced water loss from vascular tissue

• Pericycle - single layer of cells inside endodermis point of origin of lateral (branch) roots mostly of parenchyma cells

• Vascular Tissue - xylem & phloem function for transport of water and minerals monocots & dicots distinctly

Contrast the root anatomy of an herbaceous monocot and dicot.

dicots: pattern of xylem at center with radiating arms phloem filling in area between xylem arms

monocots: similar, but center cells do not specialize to xylem typically more arms of xylem appear as alternating xylem & phloem in a ring and parenchyma cells at center

Describe the basic development process of a root.

Root Cap: dead cells at very root tip protection of developing root cells rubbed off as roots elongate replaced by new cells produced

Zone of Cell Division: active meristematic region of root easily seen as cubic cells

Zone of Cell Elongation: little cell division, cells become elongate cells begin differentiation

Zone of Cell Specialization: cells specialize into specific tissues of root

What does it mean for a stem to be semi-woody?

semi woody tissue is the light brown material, pith is white material at center semi-woody is when the cambium develops to produce additional xylem and phloem, but for only one year

Distinguish between 1o and 2o xylem.

Primary develops from the apical meristem, while secondary develops from the cambium

2o xylem is produced toward the inside making Wood

What makes stems woody?; What is wood?

a) produced by gymnosperms and dicot angiosperms only

b) production of xylem and phloem is from the vascular cambium

c) 2o phloem is produced toward the outside making the Bark

d) 2o xylem is produced toward the inside making Wood

e) much more 2o xylem produced than 2o phloem hence the wood is think and bark thin

Annual rings are a result of two distinct times of annual growth

Distinguish between spring and summer growth.

spring growth - spring spurt of growth

• large cells

• low cell density - lighter color = Early wood

summer growth - slower growth in summer

• smaller cells produced

• higher cell density - darker color = Late wood

Describe how growth rings develop?

Large cells develop in the spring with warm moist weather, smaller cells are produced in the summer, thus closer together and look darker

The size of annual rings related to annual weather conditions: warm, wet years - more growth cool, hot or dry summers - less growth true of both stems and roots

What is bark?

Bark = all tissues outside vascular cambium

Define the following terms of woody stems: hardwood, heartwood, sapwood, softwood, vascular cambium, vascular rays

• Heartwood: Older, non-functional central wood with dead cells; dark-colored from oxidized tannins.

• Sapwood: Younger, functional outer wood with living cells; actively conducts water.

• Softwood: Gymnosperm wood consisting primarily of tracheids (no vessels), narrow one-cell-wide rays, and resin canals.

• Hardwood: Angiosperm wood containing large vessel elements, thick-walled tracheids, wide rays, and no resin canals.

• Vascular Cambium: Lateral meristem generating secondary xylem (wood) inward and secondary phloem outward.

• Vascular Rays: Radial rows of parenchyma cells that facilitate the lateral transport of water and nutrients.

Name and describe the three basic tissues of a leaf.

Epidermis - surface layer of cells, both above & below, no chloroplasts in cells, Cuticle

Mesophyll - photosynthetic tissue loaded with chloroplasts

Vascular bundles - phloem & xylem

Describe the three leaf venation patterns of plants. Which typically fit into monocots and/or dicots?

parallel - all veins run entire length of leaf, side-by-side

typical of monocots

palmate - veins branch out from base of blade

typical of some dicots

pinnate - veins branch out from a main central vein running blade length (like a feather)

typical of some dicots

What weather changes stimulate color changes to initiate?

autumn approaches, we notice shorter days and cooler weather, Shorter days lead to less daylight and less light intensity, Cooler nights signal a further change result is the breakdown of chlorophyll

Why do plants produce anthocyanin in their leaves during the fall?

• Absorb harmful light rays (inc UV)

• Act as an antifreeze

• They are not a photosynthetic pigment

What fall weather patterns enhance color production by plants?

• Warm sunny days and cool evenings (enhances production of anthocyanin)

• The lack of a hard freeze

What is the general equation for photosynthesis?

light

CO2 + H2O ---------------------------> C6H12O6 + O2

chlorophyll, enzymes

What are the three possible fates of a photon of light as it gets to a leaf?

TRANSMITTED – goes through leaf

REFLECTED – bounces off leaf surface

ABSORBED – causes an effect in the leaf

What is a pigment complex?

Chlorophyll a and accessory pigments that facilitate the absorption of light energy

In one sentence, what happens in the light requiring phase of photosynthesis?

Light is absorbed and converts it into chemical bonds of ATP and NADPH

Explain the process by which light energy can be converted into chemical bond energy.

1) quantum of light absorbed by pigment complex

2) energy directed to chlorophyll a molecule

3) chlorophyll a molecule is "excited" and loses an e-

4) e- moves toward and is picked up by an acceptor molecule

5) the acceptor molecule - e- combination is unstable and e- is given off; the e- now has less energy due to interaction

6) the e- moves to another acceptor molecule to repeat process

7) the loss of energy from the e- during one of the interactions is enough energy for a Phosphate (Pi) to be added to ADP  ATP (occurs due to proton motive force – see p.174)

8) after several repetitions of process the e- comes to a final electron acceptor where it is stable and remains

Distinguish between cyclic and noncyclic photophosphorylation.

CYCLIC PHOTOPHOSPHORYLATION (simpler system of prokaryotic organisms)

• pigment complex = Photosystem I (P700)

• final acceptor = Photosystem I (P700)

NONCYCLIC PHOTOPHOSPHORYLATION

• pigment complex = Photosystem I (P700) and Photosystem II (P680)

• final acceptor of Photosystem I = NADP+

• final acceptor for Photosystem II = Photosystem I (P700)

• Photosystem I restocked with electrons by Photosystem II

• Photosystem II restocked by splitting H2O

• H2O  H+ + O- (eventually becomes O2)

In one sentence, what happens in the nonlight requiring phase of photosynthesis?

Takes energy and CO2 to make sugar.

What is the Hatch-Slack Pathway?

Addresses photorespiration when midday heat stops gas exchange, leading to low and high$O_2$. RuBP carboxylase binds $O_2$ instead of $CO_2$ ($O_2 + RuBP \rightarrow 1\,\text{phosphoglycolate} + 1\,\text{PGA}$ rather than $CO_2 + RuBP \rightarrow 2\,\text{PGA}$ ), which breaks down phosphoglycolate into $CO_2$

Why are C3 and C4 plants named as such?

1) Plants able to complete Hatch-Slack and Calvin Cycles = C4 plants

first stable product is a 4-carbon molecule (Oxaloacetate)

2) Plants only able to complete Calvin Cycle = C3 plants

first stable product is a 3-carbon molecule (Phosphoglycerate)

What is Crassulacean Acid Metabolism (CAM)?

Some C4 plants have entire process occur in each cell – separation in time not space

Night – CO2 fixed into Malate when stomates open

malate stored in vacuoles

Day - Malate transfers CO2 to RuBP