Module 2: Plant Nutrition, Gas Exchange and Transport Flashcards
What is the word equation for photosynthesis?
carbon dioxide + water -> oxygen + glucose
Why is gas exchange vital for the survival of plants?
Plants need to exchange oxygen and carbon dioxide between their cells and the environment to allow photosynthesis and respiration to occur.
What is the waxy cuticle of a leaf?
The thin, protective outer layer consisting of a lipid produced by plant cells.
What is the upper epidermis?
A tissue layer on the upper side of a leaf. It provides structural support and allows light to pass through.
What is the palisade mesophyll?
The primary site of photosynthesis.
What is the spongy mesophyll?
Cells surrounded by air space to allow gases to diffuse through to the palisade mesophyll. The secondary site of photosynthesis.
What is the lower epidermis?
A tissue layer on the lower side of a leaf. Aids structural support.
What is the stoma? (Plural stomata)
Small holes in the leaf that allow gases to enter and exit. Allow the loss of water vapour.
What are guard cells?
Open and close to stomata in response to environmental conditions. There are two found at each stoma.
What is the role of a leaf?
A type of plant organ resposible for photosynthesis and gas exchange.
What is the widest surface or blade of a leaf?
Lamina
What is the petiole?
The structure connecting the leaf to the stem of the plant.
What is the midrib?
Central vein of the leaf.
What is the role of veins in a leaf?
Provide transport within the leaves and plant.
What is the margin of a leaf?
The outer edge of the leaf.
Why might stomata from plants of different environment be different?
They may have diffeent water availability, and as a result have altered the number of stomata present on their leaves.
What happens when the stomata is open?
Gases are able to enter the plant, however, water can be lost.
What happens when the stomata is closed?
No gas is able to enter the plant.
What is the main purpose of nitrates in plants?
Making amino acids thst are needed to build proteins. Also used as a building block for chlorophyll.
What is the main purpose of magnesium in plants?
It is used to make chlorophyll.
What is the main purpose of phosphorus in plants?
Its used in energy transfer using ATP. It also aids maturation and growth of the plant.
What is the main purpose of potassium in plants?
To catalyse many different reactions, including photosynthesis. It also is used inside guard cells to control the opening and closing of stomata.
What is the main purpose of calcium in plants?
To strengthen cell walls.
What are two ways that plants gain nutrition?
Via photosynthesis and absorption from the soil.
Are plants autotrophs or heterotrophs?
Autotrophs.
What gases do plants need to take in?
Carbon dioxide and oxygen.
What gases do plants excrete?
Carbon dioxide and oxygen.
Why do some plants consume insects?
To compensate for low nutrient levels in their soil.
Are carnivorous plants still classified as autotrophs?
Yes, as they still use inorganic carbon sources.
What are the two main purposes of roots?
Stabilise the plant in the soil and to absorb water and mineral nutrients from the soil.
What do roots do in root vegetables?
To store excess sugars as starch.
What are the two main types of roots?
Tap roots and fibrous roots.
What are the tap roots?
The one main root that descends vertically in the soil.
What are the fibrous roots?
Smaller roots that extend out of the tap root to form a complex network relatively close to the surface of the soil.
What are vascular bundles?
Plant “veins” containing xylem and phloem vessels.
Why would a root require vascular bundles?
To transport water and mineral nutrients (from the soil) and sugars (from the leaves).
How does SA:V ratio affect absorption in root hairs.
Root hairs are long and thin, giving them a high SA:V ratio. This increases the ability of substances to absorb into the plant.
What are root hairs?
Specialised cells that increase the uptake of water and minerals from the soil.
What are the two vascular tissues of plants?
Xylem and phloem.
What does xylem carry?
Water and mineral nutrients.
What does phloem carry?
Sugars.
What is the role of guard cells?
To open and close the stomata - dependant on whether the plant needs more carbon dioxide.
How do plants adapt to low water availability?
Thin leaves to reduce surface area. Opening stomamta at night and closing it during the day.
How do plants adapt to lack of light?
Broad, wide leaves to absorb as much light as possible.
How do some plants adapt to lack of nitrogen in the soil?
Develop abilities to digest insects by producing enzymes to break them down. These are carnivorous plants, for example, the venus fly trap.
What direction does water move in the xylem?
Up.
What direction do sugars move in the phloem?
Up and down.
What cells make up the xylem?
Dead cells, strengthened by lignin.
What cells make up the phloem?
Companion cells, separated by sieve plates.
Are xylem cells living or dead?
Dead.
Are phloem cells living or dead?
Living.
Which plant organ absorbs water fromt he soil?
Roots.
Where do plants lose water?
The leaves.
How do plants lose water?
Transpiration drawing water from the leaf through the stomata.
What process do plants use to make sugars?
Photosynthesis.
What are the outer walls of the xylem strengthened by?
Lignin.
What do the pits in the walls of the xylem do?
Aid water movement in and out of the xylem.
What is the movement of water against gravity in the xylem called?
Transpiration-cohesion-tension theory.
What is transpiration?
The loss of water from plants by evaporation of water vapour through the stomata of plant leaves.
How does transpiration affect transpiration-cohesion-tension theory?
It pulls water up from the roots, creating negative pressure (tension).
How does the “stickiness” of water affect cohesion in transpiration-cohesion-tension theory?
Water molecules are attracted to each other, and have temporary intermolecular bonds that help them “stick” to one another.
What is cohesion?
The ability of water molecules to “stick” to other water molecules due to high intermolecular forces.
What is adhesion?
The attractive forces between water and other non-water molecules.
What is negative pressure (tension)?
When an area has a lower pressure than the areas surrounding it. This creates a “pulling” force.
What generalised path does water take to enter and move through a plant?
Soil -> roots -> stem -> leaves
Describe the structure of the xylem.
Made of dead cells, joined together with their ends removed to create a hollow tube. The walls are thickened and strengthened by lignin.
Where does tension occur in the plant?
The leaves.
How do the phloem vessels affect cellular respiration?
It transports sugars up and down the plant, so that cells throughout the plant can respire.
What molecule is glucose usually broken down into before being transported through the phloem?
Sucrose.
Where is glucose converted into sucrose?
The leaves.
What are the living cells that make up the phloem tube called?
Sieve tube elements.
What type of cell is found on the outside of the phloem tube?
Companion cells.
What are sieve tube plates?
Perforated barriers between cells, allowing sugar movement through their holes.
What are sugar sinks?
Places in the plant that need sugars. These are most likely areas if the plant that are growing and therefore have increased energy needs.
What are some other sugar sources, not including leaves?
Stored sugars in the form of starch in the root of root vegetables.
What are sugar sources?
Places of the plant that produce/store sugar.
What are two examples of sugar sinks in a plant?
Root tips at the bottom of the plant and the shoots that the top of the plant.
What is the movement of sugar sources to sinks called?
Translocation.
Why is active transport required to move sugars from sources into the phloem?
The sugars are moving against the concerntration gradient, from the source into the phloem.
Why does sugar move passively our of the phloem into sinks?
Sugar molecules are moving down the concerntration gradient from the phloem into sinks.
What is the first stage of translocation?
Plants obtain sugars through photosynthesis. These sugars are primarily found in the leaves, or in sugar stores.
What is the second stage of translocation?
Active transport is used to move sugars from sugar sources into the phloem, against the concerntration gradient.
What is the third stage of translocation?
The increased concerntration of sugars in the phloem causes water to move passively into the phloem from the xylem via osmosis.
What is the fourth stage of translocation?
The increased fluid volume in the phloem creates a temporary increase in pressure - this causes materials in the phloem to move towards the sinks.
What is the fifth stage of translocation?
Sugars move into regions where they are required (sinks) - by either passive or active transport.
What is the sixth stage of translocation?
The decreased concerntration of sugars in the phloem causes water to move passively back into the xylem, reducing pressure in the phloem.
What is the energy source of plants?
Light energy (in the form of sunlight).
What are the two sources of nutrients in plants?
Sugars from photosynthesis and mineral nutrients from the soil.
How are gases transported in a plant?
Gases move directly from the environment into tissues and then diffue from cell to cell.
Is transport in the xylem active or passive?
Passive.
Is transport in the phloem active or passive?
Active and passive.
What are vascular plants?
Plants with a xylem and phloem.
