Plant structures/diseases Flashcards
What is the purpose of a leaf?
To photosynthesis so it can produce its own food, glucose.
What is a leaf adapted for? (4)
-To absorb lots of sunlight for photosynthesis-To allow CO2 to enter during the day-To allow O2 to escape during the night-To control how much water the plant loses.
What are the 4 adaptation features a leaf has and what are their purposes?
Green- contains chlorophyll for photosynthesis, it absorbs light energy from the sun to be used in photosynthesis to make the plant’s food.Flat/thin- to maximise the plant’s surface area to volume ratio, maximises the amount of sunlight and CO2 the leaf is in contact with and absorbs helping photosynthesis, also keeps the diffusion distance short.Veins- the plant’s transport system consisting of phloem and xylem tubes, xylem cells transport water and minerals from the soil to the leaves for photosynthesis to occur and the phloem cells transport the food that is produced to growing parts of the plant.Has a waxy cuticle- covered in wax to prevent water loss from transpiration, limits the amount of evaporated water vapour from escaping.
Which is closer to the upper epidermis of a leaf; phloem or xylem tubes?
Xylem tubes are at the top of the vein.
What is a phloem cell and what are its features?
A phloem cell is specialised to transport the food (glucose) made from photosynthesis to the growing parts of the plant that need the nutrients.Phloem cells have sieve like end walls which helps the nutrients to absorb into the plant as it gets transported, they also have companion cells next to them which have many mitochondria to supply them with enough energy to absorb the food, these also help the phloem cells to withstand the pressure and friction of the continuous flow
Describe the structure of a root.
Root hair cells- to take in water and mineral ions by osmosis and active transport. It has phloem tubes (that takes food from the leaf down to the growing parts of the root) on the outer interior of the root and a xylem tube running in the centre of the root to transport the water and minerals upwards. It has a root cap to protects the end of the root tip as it grows through the soil.
Describe the structure of a stem.
There’s a ring called the cambium that makes new phloem and xylem cells. On the inside of the ring are xylem tubes and on the outside there are phloem tubes, together they are celled a vascular bundle. They have an epidermis surrounding the whole stem for protection and to prevent water loss.
What is osmosis?
The movement of water through a semi-permeable membrane from a dilute solution to a concentrated solution.
Describe transpiration:Explain the process of transpiration with the first point being that the water vapour diffuses out.
The movement of water and its dissolved mineral ions up a plant through xylem tubes.
-Water vapour diffuses out into the environment through the stomata
-The water evaporates off of the surface of the spongy mesophyll, reducing their water content
-Water moves from cell to cell due to osmosis to replace the water that has been lost.
-Water gets pulled out of the xylem tube through osmosis.
-Water is pulled up the xylem tubes due to the cohesion between the water molecules.
What are the factors that effect transpiration and how:
Temperature- the heat energy gets transferred into kinetic energy causing the water to evaporate more and the stomata open, allowing lots of transpiration to occur.
Wind speed- the higher the wind speed the greater the diffusion gradient as water vapour doesn’t collect as much near the plants leaves. this make diffusion faster and therefore transpiration increases
Light intensity- the sunnier it is the more that stomata open
Humidity- the more humid it is the less transpiration occurs as it decreases the concentration gradient in the atmosphere
What experiment would need to be carried out to measure how much a plant transpires?
Get a potometer
What are symptoms of a plant having a disease? (7)
-leaves falling early
-discolouration on leaves and stem
-stunted growth
-visible pesticide
-growths
-malformed stems
-areas of decay and rotting
Explain three ways how we can detect that a plant has a communicable disease:
-comparing symptoms to those on a gardening manual (personal scale/ gardens)
-take samples of plant to undergo a DNA analysis which can identify what kinda of pathogen it has (scientific and agricultural scale / forests and crops)
- using test kits that has monoclonal antibodies that detect the type of pathogen easily and quickly.
Explain three ways how a plant can have a non-communicable disease:
Lack of Nitrates-needed to convert sugars into proteins
Lack of Magnesium-needed to make chlorophyll for photosynthesis
Lack of Potassium- needed so the plant can produce fruits and flowers
How does a cellulose wall defend a plant?
Helps defend and create a barrier to resist invasion by microorganisms.
