Biology C-3

Question 1

Photosynthesis

Answer 1

Conversion of light energy from the sun to chemical energy stored in sugar and other organic molecules
-Occurs in Chloroplast

Question 2

Root System

Answer 2

Organ- Roots
Function- Anchors plants to soil, absorbs minerals + water and stored carbohydrates

Question 3

Shoot System

Answer 3

Organs- Stems and Leaves
Function- Absorbs CO2 and light from above the ground
-Stem: Supports leaves and reproductive structures
-Leaves: Photosynthetic organ

Question 4

Tissues

Answer 4

Dermal- Outer protective covering
Vascular- Carriers out long distance transport of materials between root and shoot system
Ground- Storage, photosynthesis and support

Question 5

Cuticle

Answer 5

Tissue Type- Dermal
Function- Waxy substance that costs epidermal cells. Helps prevent water loss

Question 6

Upper Epidermis

Answer 6

Tissue Type- Dermal
Function- A one cell thick, layer of tightly packed transparent cells on upper side of leaf that protects against mechanical damage and pathogens

Question 7

Palisade

Answer 7

Tissue Type- Ground
Function- One or more layers of tightly packed long narrow cells with many chloroplasts. Where most photosynthesis occurs

Question 8

Vascular Bundle

Answer 8

Tissue Type- Vascular
Function- Series of tubes visible as leaf veins. Contain xylem and phloem that transport fluids

Question 9

Xylem

Answer 9

Tissue Type- Vascular
Function- Tubular elongated cells that are dead. Transports water upward from roots to leaves

Question 10

Phloem

Answer 10

Tissue Type- Vascular
Function- Long narrow cells that are alive. Transports sugars produced by the leaves to various parts of the plant where they are needed

Question 11

Lower Epidermis

Answer 11

Tissue Type- Dermal
Function- A one cell thick, layer of tightly packed transparent cells on lower side of leaf that protects against mechanical damage and pathogens

Question 12

Spongy Tissue

Answer 12

Tissue Type- Ground
Function- Layers of round loosely packed cells containing chloroplasts, Located below palisade tissue cells. Carry out photosynthesis. Air space in between all for gas transport

Question 13

Stomata

Answer 13

Tissue Type- Dermal
Function- Small openings in epidermal layer that open and close to allow gas in and out of the leaf. Each stomatal pore is flanked by two guard cells that control diameter of stoma by changing shape

Question 14

Absorption by roots and transport to xylem

Answer 14

Active transport of minerals into the roots causes water to move into the roots by osmosis
- Root hairs increase SA

Question 15

Bulk Transport - Root pressure

Answer 15

Accumulation of water in root xylem that pushes sap up stem towards the leaves (minor mechanism)

Question 16

Bulk Transport - Cohesion

Answer 16

Tendency of water molecules to stick to other water molecules
-Pulls a column of water up to leaves

Question 17

Bulk Transport - Adhesion

Answer 17

Tendency of water molecules to stick to certain surfaces
-prevents sap from falling back down (resist’s gravity)

Question 18

Sugar Transport

Answer 18

Loading of Sugar- Sugars produced by sugar source are transported to phloem vessel by active transport

Uptake of water- Osmosis causes water to move into the phloem vessel increasing pressure inside the vessel

Bulk transport- Pressure and concentration gradients move the phloem sap toward the sugar sink

Unloading of sugar- Increasing pressure forces the phloem sap out the vessel into neighbouring cells

Question 19

Gas Exchange (Leaves)

Answer 19

Most gas exchange occurs through stomata in epidermal layer
- CO2 is transported into leaf and O2 is transported out through passive transport

Question 20

Gas Exchange (Stems and Roots)

Answer 20

Lenticles- Lense shaped opening in bark of woody plants that enable gas exchange

Question 21

Transpiration

Answer 21

Loss of water through diffusion and evaporation
- Large sa, High sa/v ratio and stomata important for photosynthesis but also increase water loss

Question 22

Controlling stomata

Answer 22

Open- In moist environments, guard cells open all
-Gain water, become turgid and open

Close- In dry environments, guard cells close
-Lose water, become flaccid and close

Question 23

Tropism

Answer 23

Any growth response that results in plant organs curving toward or away from stimuli
- Positive Tropism - Growth toward the stimulus
- Negative Tropism - Growth away from the stimulus

Question 24

Phototropism

Answer 24

Growth toward or away from light

Question 25

Phototropism - Darwin and Darwin

Answer 25

Problem: What part of the plant senses where light is coming from?

Results:
- Tip removed - No phototropism
- Tip covered by opaque cap - No phototropism
- Tip covered by transparent cap - Positive phototropism
- Stem covered by opaque shield - Positive phototropism

Conclusion: The tip of the seedling detects light and sends a signal down to the stem to control growth

Question 26

Phototropism - Boysen-Jensen

Answer 26

Problem: What type of signal controls stem growth

Method: Tip separated from stem by different barriers

Results:
- Gelatin (permeable) - Positive phototropism
- Mica (impermeable) - No phototropism

Conclusion: The signal is a mobile chemical because it passes through the gelatin (permeable barrier), but not the mica (impermeable barrier)

Question 27

Frits Went

Answer 27

Problem: What is the chemical signal

Method:
- Removed the seedling tip and placed it on an agar block to allow the chemical messenger to diffuse into the agar
- Agar block placed on different parts of the decapitated stem in the dark

Results:
- Centered - Grew straight
- Off-centered - Curved away from the side with the agar block

Conclusion: Auxin is the chemical messenger, hormone, that causes elongation of the cells on the darker side

Question 28

Gravitropism

Answer 28

Growth in response to gravity
-Roots display positive gravitropism
-Stems display negative gravitropism