Topic 6 - Plant Structures and their Functions Flashcards
Why are photosynthetic organisms producers of biomass
Because they use energy from the sun to produce glucose
What substances are produced from glucose and their roles in the plant
energy which is used for respiration
recall the equation for photosynthesis
6CO2 + 6H2O —> C6H12O6 + 6O2
Why is photosynthesis an endothermic reaction?
AS energy is taken in during the reaction
How are leaves and their cells adapted for photosynthesis
Palisade layer has lots of chloroplasts so theyre near the top of the leaf
broad with large surface area exposed to light for photosynthesis
What are the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis
Light intensity- when high intensity, rate of photosynthesis speeds
Carbon dioxide- two little slows it down as its a raw material needed
Temperature- If too hot enzyme denatures too low enzymes dont work
Why is the rate of photosynthesis inversely proportional to the distance from light source?
because as distance increases the photosynthesis rate decreases 1/distance 2
How are root hair cells adapted to their functions
millions of microscopic hairs which gives plant large surface area to absorb mineral ions through active transport and osmosis
what are the 3 transportational processes
osmosis diffusion and active transport
what is the concentration gradient
The direction osmosis and diffusion take from a high to low concentration.
active transport goes against the concentration gradient
What is active transport used for
To transport food molecules such as sucrose from a low to high concentration
How is a Xylem tube adapted for its function
dead cells joined together end to end with no end walls to take water from roots to stem and leaves.
strengthened with lignin
carry mineral ions too up the transpiration stream
What is the transpiration stream
Movement of water from the roots through xylem and out of the leaves
Why is the phloem tube adapted to its function? What is translocation
Elongated living cells with small pores on end walls so food substances can diffuse through.
they transport food substances made in leaves to other parts of the plant through process of translocation
What is transpiration
caused by evaporation and diffusion
occurs usually in leaves
its the loss of water from a plant
What effects the rate of transpiration
Light intensity- brighter light the greater the rate as stomata close when its dark.
Temperature- warmer means faster transpiration as particles have more energy to evaporate and transpire
Air flow- better the air flow the more transpiration as water vapour is swept away maintaining low water concentration on surface of leaf so diffusion occurs faster
How can you measure the rate of transpiration
using a potometer and record position of air bubble. start time and measure distance moved. calculate the speed of bubble
What are the different tissues in a leaf
Waxy cuticle, upper epidermis, palisade mesophyl tissue, lower epidermis, stomata on base
What are the functions of these layers of leaves
Waxy cuticle- reduces water loss
upper epidermis- light is allowed through as this layer in transparent
Palisade layer- lots of chloroplasts near top so lots of light
Spongy mesophyll tissue- contains air space which increases the rate of diffusion
lower epidermis- lots of stomata which lets CO2 diffuse directly into the leaf
What are some adaptations plants have to living in extreme conditions
- Small leaves or spines to reduce surface area to reduce evaporation and stop predators eating
- Curled leaves/hairs to reduce air flow on surface which reduces diffusion
- Thick waxy cuticles to stop water loss by evaporation
- Few stomata that only open at night to reduce evaporation
- Stomata in sunken pits to reduce air flow to them
What are the names of 3 plants hormones
-gibberellins ethene and auxins
Identify positive and negative tropisms
Positive phototropisms- Shoots
Negative- roots
positive gravitropsims- Roots
negative shoots
How do auxins cause phototropism
auxins in tips of shoots makes all side elongate so a taller shoot gets more light
How can plant growers use auxins
selective weed killers- only effect broad leaf plants- disrupts plant growth
growing cuttings from rooting powder- conatins auxins which produce shoots very quickly and can create clones
How can plant growers use Gibberellins
-controlling seed germination- make plants flower earlier or under conditions they wouldnt normally flower it stimualtes SEED GERMINATION
(can also reduce flower formation to improve fruit quality)
-proudcing seedless fruit- applied to unpollonated flowers to so fruit grows but seeds dont
-Controlling seed germination - getting seeds to germinate at time of year they would normally
How can we artificially ripen fruit with hormones
Controlling ripening of fruit- ethene is added to fruit on the way to the supermarket so when they get there the fruit will be perfect on the shelves
Advantage of using plant hormones in fruit farming?
- Get fruit at times of year where conditions wouldnt usually be right,
- produce seedless fruit
- produce clones of one plant
Disadvantages of Plant hormones in fruit farming
- Harmful to environment- fertilisers and chemicals can leak into waters
- fruit may be poor quality
- traditional farmers out of business
