Chapter 6-7 plants

Photosynthesis

process by which plant make carbohydrates from carbon dioxide and water using energy from light in the presence of chlorophyll to produce glucose and oxygen 

cuticle

waxy material that prevents water evaporation from leaf

upper epidermis

Transparent with no chlorophyll to allow passage of sunlight to palisade mesophyll layer for max rate of photosynthesis

palisade mesophyll

1. contains many chloroplast for max rate of photosynthesis

2. cells are closely packed with no air spaces for max absorption of sunlight for max rate of photosynthesis 

spongy mesophyll layer

cells are rounded and loosely packed with large air spaces to allow easier diffusion of gases through leaf

Stomata

Opening to allow carbon dioxide to diffuse in and oxygen out for photosynethsis by diffusion down conc gradient

guard cells

Gaseous exchange

xylem vessels transport what

mineral ions and water

what does phloem translocate

sucrose and amino acids

Chlorophyll

chlorophyll traps light energy and converts it to chemical enegry (glucose) with the help of enzymes

Limiting factor

is an environmental factor being as co2 temp light present in a short supply that limits the rate of a reaction like growth or photosynthesis

What’re the limiting factors

light intensity

temp

conc of carbon dioxide 

Why is light intensity a limiting factor

Light energy is absorbed by chlorophyll to be converted to chemical energy (glucose)

Why is carbon dioxide a limiting factor

Its a raw material for photosynthesis

Why is temp a limiting factor

affects enzyme activity 

Xylem vessels adaptation

1. Made up of dead cells have no nucleus or cytoplasm so water and minerals flow with least resistance

2. have no end wall so water and minerals will flow with least resistance

3. have lignin which is impermeable to water and support the stem

4. have pits for lateral movement of water

Adaptation of root hair cell

1. Have long finger like projection to increase surface area for faster rate of absorption 

2. have many mitochondria to release energy for active transport of minerals

Transpiration 

loss of water from plant leaf by Evaporation of water at surface of spongy mesophyll layer followed by diffusion of water vapor through stomata down conc gradient 

factors affecting rate of transpiration

1. Humidity

2. temp

3. light intensity 

4. wind speed

How does Humidity affect transpiration

Decrease in humidity increase in the diffusion gradient for H20 vapor through stomata

How does temp affect transpiration

Increase in temp causes water molecules to gain kinetic energy so faster rate of diffusion of water vapor through stomata

How does light intensity affect transpiration

As light affects opening of stomata so brighter light (wider opening) allows more diffusion of water vapor through stomata so more water loss

How does wind speed affect transpiration

Higher wind speed causes increase in transpiration

The water needs water more

1. maintain cell turgidity

2. transport of minerals

3. raw material for photosynthesis

Translocate 

Translocation of sucrose of amino acids through phloem tubes from region of production (source) to regions of utilization to regions of storage (sink)

hydrophytes

large and many air spaces: for floating of plant and to allow gas diffusion to take co2 and for trapping sunlight for photosynthesis

Thin cuticle: as there is no need to reduce water loss

stomata found on upper surface of leaf: to allow diffusion of gases from the air and prevent entry of water