Plant Tissues, Organs & Systems Flashcards
All 23 cards in this deck
What is the function of palisade mesophyll tissue in a leaf?
It is the main site of photosynthesis — its cells are packed with chloroplasts and sit near the top of the leaf.
How is spongy mesophyll tissue adapted to its function?
It contains many air spaces, giving a large surface area for gases to diffuse to and from the cells.
How is the upper epidermis of a leaf adapted to its function?
It is thin and transparent so light passes through to the palisade layer, and is covered by a waxy cuticle that reduces water loss.
Where is meristem tissue found in a plant, and what is its role?
At the growing tips of shoots and roots; its unspecialised cells divide and can differentiate into any plant tissue.
True or false? Palisade mesophyll cells are the most transparent cells in a leaf.
False. Epidermal cells are the most transparent; palisade cells are packed with chloroplasts.
Which two transport tissues are found in the veins of a leaf?
Xylem and phloem.
Which three plant organs form the organ system for transport of substances around a plant?
The roots, stem and leaves.
How is a root hair cell adapted for the uptake of water and mineral ions?
A long hair-like extension gives a large surface area, the cell wall is thin, and it has many mitochondria to release energy for active transport.
By which process does a root hair cell take up water, and by which process does it take up mineral ions?
Water by osmosis; mineral ions by active transport.
Describe the structure and function of xylem tissue.
Hollow tubes of dead cells strengthened by lignin; they carry water and mineral ions from the roots to the stems and leaves.
True or false? Xylem transports dissolved sugars from the leaves to the rest of the plant.
False. Xylem carries water and mineral ions upwards; phloem carries dissolved sugars.
True or false? Root hair cells contain chloroplasts.
False. They are underground and receive no light, so they have no chloroplasts.
What is transpiration?
The evaporation of water from the leaf cells and its diffusion out of the leaf through the stomata.
What is the transpiration stream?
The movement of water taken in by the roots, up the plant through the xylem, and lost from the leaves.
What is the role of the stomata and guard cells?
To control gas exchange and water loss — guard cells open and close the stomata.
True or false? Stomata are usually almost closed at night.
True. There is no light for photosynthesis, so closing them reduces water loss.
Which four environmental factors affect the rate of transpiration, and what change in each increases the rate?
Higher temperature, higher light intensity, more air movement and lower humidity all increase the rate.
What are the steps to calculate the rate of transpiration from water uptake data?
e.g. a shoot takes up cm of water in hours
- Find the volume of water taken up: cm
- Divide by the time taken:
- Give the answer with units: cm per hour
What is translocation?
The movement of dissolved sugars (food molecules) through phloem tissue.
What does phloem tissue transport, and where to?
Dissolved sugars from the leaves to the rest of the plant, for immediate use or storage.
How is phloem tissue structured?
Tubes of elongated cells with pores in the end walls, so cell sap can move from one cell to the next.
True or false? Translocation only moves sugars downwards to the roots.
False. Sugars are moved to all parts of the plant, including growing shoots as well as storage organs.
Which transport tissue is made of living cells: xylem or phloem?
Phloem — xylem is made of dead, hollow tubes.