Plants 🌱 Flashcards
Word equation for photosynthesis
Carbon dioxide + water ————> glucose + oxygen
Symbol equation for photosynthesis
6CO_2 + 6H_2O ————> C_6H_12O_6 + 6O_2
What is the glucose produced in photosynthesis used for
To make starch
What happens when photosynthesis stops
Starch is broken down into simpler substances which are moved into the cytoplasm and used to make SUCROSE
What is sucrose used to make
Starch
Other molecules for the plant (eg. Cellulose lipids or proteins)
glucose for respiration (to release energy)
Is photosynthesis endothermic or exothermic
Endothermic
What are the 4 key features in the structure of a leaf
Wide and flat
Lots of veins
Stomata on the underside
Thin
How does leaves being adapted to be THIN help the plant
Gases can reach cells easily
How does leaves being adapted to have STOMATA on the underside help the plant
Allows gas exchange 
How does leaves being adapted to be WIDE AND FLAT help the plant
Large surface area and absorbs as much light as possible
How does leaves being adapted to have many VIENS help the plant
Carry water to the cells and carry glucose away
What is the waxy cuticle
The covering on plant leaves to help to plant retain water (water proof)
What is the epidermis
Provides a protective layer against injury water loss & infection
Also thin & transparent to allow light to enter
What is the Palaside layer
Tightly packed layer of cells beneath the cuticle and upper epidermis
Contains the majority of chloroplasts which use chlorophyll to perform photosynthesis
What is the spongy Mesophyll
They are covered by a thin layer of water.
Gases dissolve in this water as they move in and out of cells
What is the vascular bundle
Network of veins (xylem and phloem) which support the structure of the leaf and transport substances to and from the cells
What are the stomata and guard cells
Stomata are pores in the epidermis that function as gateways linking internal and external gases. Guard cells control wether the stomata are opened or closed
What happens to guard cells in the daytime
Stomata are open to enable gas exchange as the guard cells have taken in water by osmosis and are TURGID
What happens to the guard cells at night
Stomata are closed to prevent water loss. This is because the guard cells have lost water by osmosis and are FLACCID
How does increasing light intensity affect the rate of photosynthesis
It increases the rate of photosynthesis until a limiting factor becomes short in supply
How does the amount of CO2 concentration affect the rate of photosynthesis
If the rate of CO2 increases the rate of photosynthesis will also increase
How does temperature affect the rate of photosynthesis
Chemical reactions involved in photosynthesis are controlled by enzymes.
As the temperature increases collisions between enzyme and a substrate increase and therefore so does the rate of photosynthesis.
At high temperatures enzymes become DENATURED and this will decrease the rate of photosynthesis
Light intensity is measured as 600 Lux at a distance of 20 cm from a lamp
Calculate the light intensity at a point 40cm away from the lamp
So you are doubling (x2) the distance…
Therefore the light intensity is 1/4 (1/2^2) the original
New light intensity = 600÷4 = 150 lux
What is the function of the xylem vessel
Carries water and minerals
What is the function of the phloem vessel
Carries dissolved sugars
Describe the structure of a xylem vessel
Hollow tubes
Describe the structure of a phloem vessel
Tubes have sieve plates
Is a xylem vessel dead or alive
Dead
Is a phloem vessel dead or alive
Alive
How is the xylem vessel supported
Thickened with cellulose and lignin
How is a phloem vessel supported
Companion cells provide energy for active transport
Define translocation
Movement of dissolved sugars UP & DOWN the plant through PHLOEM
Define transpiration
Movement of water UP the XYLEM vessel
List the steps in transpiration
Water in soil ——->root hair cells ——->xylem ——->leaf veins ——->stomata
by osmosis. by osmosis. by evaporation
What is controlled by hormones in plants
Growth- roots & shoots, seed germination, leaf fall, disease resistance, fruit formation & ripening, flowering time and bud formation
What is a tropism
How plants respond to their environment
What is positive phototropism
The plant grows towards the light
this happens at the shoot tip
What is negative phototropism 
Where the plant grows away from the light
this happens at the roots
What is plant growth called when gravity is the stimulus
Gravitropism or geotropism
What is plant growth called when light is the stimulus
Phototropism
What is positive gravitropism
Where the plant grows in the direction of gravity
this happens at the roots
What is negative gravitropism
Where the plant grows opposing gravity
this happens at the shoot tips
What are auxins
One of the hormones used by plants for growth and are produced in the shoot tip
How do auxins effect the roots and shoots of the plant
In the shoots ANY concentration promotes growth
At the root high concentration inhibits growth, small concentration promotes growth
What are gibberellins
Plant hormones which are naturally released inside the seed to start germination
What do Gibberellins do
Flower growers can override photoperiodism.
They do this by spraying the plants with gibberellins
What is photoperiodism 
Response of an organism to the number of daylight hours
Some plants use this to flower at a certain time eg. When pollinators are not around
How are gibberellins useful to us
Can cause some plants to produce seedless fruits
They can also be sprayed on some plants to make them produce bigger fruits
What are minerals used for in plants
To build the complex molecules they need from minerals
What are minerals used for in animals
Need very few minerals
How are minerals absorbed
The concentration of minerals in the soil is very low.
They dissolve in water and move around the soil in solution
How are root hair cells adapted to absorb water
Osmosis- they have a large surface area thin walls and are close to the xylem cells for transporting water up the plant
What is transpiration
The movement of water through and out of a plant
What is the transpiration rate
The rate at which water escapes through the plant
How does temperature affect transpiration rate
The warmer it is the faster the water evaporates from the leaves
How does humidity affect the transpiration rate
The lower the humidity the faster the water evaporates
How does wind speed affect the rate of transpiration
The windier it is the faster moist air is taken away from the leaf surface
How does light intensity affect the transpiration rate
Transpiration is faster when the stomata are open in the light
What adaptations do desert plants have to survive extreme conditions
Thick waxy cuticle - less water loss by evaporation
Small leaves - reduced surface area for water loss
Spines - reduced surface area / deters animals from eating for water
Fleshy/swollen stem - collects and stores water
What are auxins used for commercially
Rooting powders and weed killing
