Plant Biology

Question 0

Photosynthesis

Answer 0

Light + 6CO2 + 6H2O -> glucose + 6o2

Oxygen comes from water

Light reaction: chlorophyll absorbs light (magnesium ion)

Two photosystems embedded in thylakoid membrane, light excited electrons to higher energy state, electrons move through transport chain to produce chemical energy (ATP AND NADPH)

Calvin cycle (dark reaction):

Takes co2 and makes sugars in 6 turns inside thylakoid using chemical energy from light reaction. Phase 1,2,3 is carbon fixation, reduction, and regeneration of co2 acceptor

Product is glyceralaldehyde triphosphate, so this cycle had to occur twice

Energy input for one glucose: 18 ATP, 12 NADPH

Question 1

Chloroplast

Answer 1

In the chloroplast there are:

Thylakoid (flattened sacs)

Grana (stacks of thylakoids)

Stroma (fluid surrounding)

Thylakoid space (space inside thyl)

Question 2

Plant anatomy

Answer 2

Plasmodesmata: pores in the primary cell walls of adjacent cells that allow materials to move easily

Pits: openings in secondary cell walls so plasmodesmata are exposed

Three cell types (ground tissue system):

Parenchyma are for photosynthesis

Collenchyma are for support (thicker walls)

Schlerenchyma are for support (thicker)

Two vascular tissues exist:

Xylem transports water and minerals from roots to leaves (tracheids, vessel elements)

Phloem translocates sugars to cells (sieve tube member, companion cell)

Question 3

Cohesion tension theory

Answer 3

Driving force of transport is transpiration, the evaporation of water from leaf surfaces

Question 4

Photoperiod

Answer 4

Relative length of daylight and night

Plants have a critical night length that needs to be met if they are to flower (cocklebur needs 8 hours of night)

Red light exposure can disrupt the “resting time” during night, so plants who have these conditions will not flower