Transport In Plants Flashcards
(15 cards)
What is the structure of a root hair cell?
A long and narrow extension increases surface area for rapid absorption of water and minerals.
It contains a sap vacuole to create osmotic potential and does not have chloroplasts.
What are the two types of transport vessels in flowering plants?
Xylem vessels and Phloem vessels.
These vessels are found in roots, stems, and leaves.
What is the structure of xylem vessels?
Narrow, cylindrical tubes with no cross walls, hollow lumen, made of dead cells, and strengthened by lignin.
This structure prevents collapse and allows continuous flow.
What is the function of xylem vessels?
Transports water and minerals from roots to leaves and provides mechanical support.
This is essential for plant hydration and structure.
What is the primary function of phloem vessels?
Transports food materials, mainly sucrose and amino acids, from photosynthesizing leaves to all parts of the plant.
Phloem vessels are made up of living cells.
What is the pathway of water from root to leaf?
Root hair cell → root cortex cells → xylem → leaf mesophyll cells.
Water moves via osmosis into root hair cells and travels through the xylem.
What is transpiration?
The loss of water vapour from plant leaves by evaporation at the surfaces of mesophyll cells and diffusion through stomata.
This process helps in cooling the plant and transporting minerals.
What creates a transpiration stream?
Cohesion of water molecules creates a continuous column of water, leading to a one-directional flow from roots to leaves.
Increased transpiration enhances the rate of water movement up the xylem.
What happens when a plant wilts?
Cells lose water, becoming flaccid, and the plant collapses.
Wilting closes stomata to prevent further water loss but hinders photosynthesis.
What apparatus is used to measure the rate of transpiration?
A potometer.
It measures the distance an air bubble travels in a set time.
How does humidity affect transpiration?
Low humidity increases transpiration, while high humidity decreases it.
Steeper diffusion gradient in low humidity enhances water vapour loss from leaves.
How does temperature influence transpiration rates?
High temperature increases transpiration, while low temperature decreases it.
More heat energy facilitates the evaporation of water.
What is the effect of wind speed on transpiration?
Moving air increases transpiration, while still air decreases it.
Wind removes water vapour around leaves, maintaining a steep diffusion gradient.
How does light intensity affect transpiration?
Bright light increases transpiration, while dim light decreases it.
High light intensity raises leaf temperature and opens stomata.
What is translocation in plants?
The movement of sucrose and amino acids in the phloem from sources (e.g., leaves) to sinks (e.g., roots).
This process is vital for nutrient distribution within the plant.
