AP Bio (Plants and Photosynthesis)

39) Roots vs shoots

Roots: anchor the plant, absorb water and nutrients, store food

Shoots (stems & leaves): support leaves, transport water/sugars, perform photosynthesis, reproduction

40) How roots absorb water and nutrients

Water: osmosis from soil into root cells

Nutrients: active transport through root hairs into vascular tissue

41) Primary vs secondary growth

Primary growth: lengthening of roots and shoots (apical meristems)

Secondary growth: widening/thickening of stems and roots (lateral meristems)

Cuticle

Waxy layer on leaves reducing water loss

Stoma(stomata)

Pores for gas exchange

Guard cells

Control opening/closing of stomata

Xylem

Transports water and minerals up from roots

Phloem

Transports sugars and nutrients from leaves to rest of plant

Adhesion

Water sticks to other surfaces

Cohesion

Water sticks to itself (forms column in xylem)

Transpiration

Water loss from leaves via stomata

Capillary action

Upward movement of water in narrow tubes due to cohesion & adhesion

Chlorophyll

Green pigment that absorbs light for photosynthesis

Mesophyll

Photosynthetic tissue inside leaf

Chloroplast

Organelle where photosynthesis occurs

43) Factors that increase transpiration

High temperature

Wind

Low humidity

Light intensity

Open stomata

44) Factors that decrease transpiration

Low temperature

High humidity

Water stress

Closed stomata

CALCULATE WATER POTENTIAL PROBLEMS

good luck

Formula for Photosynthesis

6CO2 + 6H2 O + sunlight -> C6 H12 O6 + 6O2.

46) Tropism and examples

Growth response to a stimulus (Directional growth or turning movement of a plant)

Examples:

Stems bending towards sunlight (positive phototropism) for photosynthesis

Roots growing downwards away from light and toward water (positive hydrotropism, negative phototropism)

Tendrils coiling around a support (thigmotropism).

Phototropism

Toward light

Gravitropism

Roots downward, shoots upward

Thigmotropism

Response to touch

47) Photoperiodism

Response of plants to the length of day/night; affects flowering and growth

49) Autotrophs vs heterotrophs

Autotrophs: make their own food (plants, algae, some bacteria)

Heterotrophs: consume other organisms for food

50) Chloroplast diagram

Include: stroma (fluid), grana (stack of thylakoids), thylakoid (site of light reactions), outer membrane, inner membrane

Look at one

51) Two stages of photosynthesis

Light reactions (light-dependent)

Calvin cycle (light-independent/dark reactions)

Light reactions (light-dependent)

a. Where does it occur?

b. List the starting substances of each stage.

c. List the products of each stage.

d. What is the waste/by-product of the light reactions?

e. How many of each end product?

f. Where do the end products go? (waste/another part of p-syn)?

g. Where is the energy? (Trace the flow of electrons.)

a) Where? Thylakoid membranes

b) Starting substances → Light, H₂O, ADP, NADP⁺

c) Products → ATP, NADPH, O₂

d) Waste/by-product → O₂

e) Quantity → Depends on number of photons; generally 1 O₂ per 2 H₂O split

f) Where end products go? ATP & NADPH → Stroma (Calvin cycle); O₂ → released as gas

g) Energy flow → Light excites electrons → electron transport → ATP & NADPH

Calvin Cycle

a. Where does it occur?

b. List the starting substances of each stage.

c. List the products of each stage.

d. What is the waste/by-product of the light reactions?

e. How many of each end product?

f. Where do the end products go? (waste/another part of p-syn)?

g. Where is the energy? (Trace the flow of electrons.)

a) Where? Stroma

b) Starting substances → CO₂, ATP, NADPH

c) Products → Glucose (C₆H₁₂O₆), ADP, NADP+

d) Waste/by-product → None

e) Quantity → 1 glucose per 6 CO₂

f) Where end products go? → Glucose used for energy/storage

g) Energy flow → ATP & NADPH provide electrons and energy to build glucose

53) Why plants are green

Chlorophyll absorbs red and blue light for photosynthesis, but reflects green light, making leaves appear green.

54) Products of cyclic vs non-cyclic electron flow

Cyclic: produces ATP only

Non-cyclic: produces ATP, NADPH, O₂

Photosynthesis takes place in plants (T/F)

True

Photosynthesis takes place in some bacteria (T/F)

True

Photosynthesis takes place in animals (T/F)

False

58) Factors affecting photosynthesis

Light intensity

CO₂ concentration

Temperature

Water availability

Chlorophyll levels