38 Questions
What is the function of root hairs in plants?
To absorb water and nutrients from the soil
The cell wall of a root hair is selectively permeable.
False
What is the main function of the cell membrane in a root hair?
The cell membrane is selectively permeable, allowing only selected substances to pass through it.
The root system of a plant consists of the main root and _______________________ roots.
lateral
What is the main component of a root hair that allows it to absorb water and nutrients?
Cell wall
Root hairs are extensions of the nucleus of an epidermal cell.
False
The_____________________ of a root hair is rigid and freely permeable.
cell wall
Match the following components of a root hair with their descriptions:
Cell wall = Rigid and freely permeable Cell membrane = Selectively permeable Cytoplasm = Contains organelles and nucleus Nucleus = Controls cell growth and division
What is the effect of sunlight on the rate of transpiration?
It increases the rate of transpiration
High humidity increases the rate of transpiration.
False
What is the cooling effect of transpiration in plants?
Transpiration helps plants cool themselves by using heat from the plant body for evaporation.
The rate of transpiration is higher when the temperature is ___________.
high
Match the factors with their effects on the rate of transpiration:
Sunlight = Increases the rate of transpiration Temperature = Increases the rate of transpiration when high Wind = Increases the rate of transpiration when blowing faster Humidity = Reduces the rate of transpiration when high
What is the process of water and minerals moving upwards from the roots to the stern called?
Ascent of sap
What is the effect of wind on the rate of transpiration?
It increases the rate of transpiration
Transpiration helps maintain the concentration of sap inside the plant body.
True
Osmosis is the process of water moving from an area of high concentration to an area of low concentration.
False
What is the role of root-hairs in the ascent of sap?
Root-hairs increase the surface area of the root, allowing for more efficient absorption of water and minerals.
Why is transpiration important in plants?
Transpiration is important for cooling the plant and maintaining the concentration of sap inside the plant body.
The central _______________ is responsible for transporting water and minerals upwards from the roots.
xylem
Match the following components with their functions:
Root-hairs = Increase surface area for absorption Central xylem = Transport water and minerals upwards Stem = Supports the plant above ground
What is the direction of the movement of water and minerals in the ascent of sap?
Upwards from the roots to the stem
The ascent of sap is an active process that requires energy.
False
What is one importance of the ascent of sap?
One importance of the ascent of sap is that it allows plants to transport water and minerals to their leaves, supporting photosynthesis and growth.
What are the three main ways water is important for plants?
Transportation, Food production, and Cooling
During photosynthesis, water combines with oxygen to produce glucose and carbon dioxide.
False
What is the cooling effect experienced under a tree on a hot summer day due to?
loss of water from leaves by evaporation
Water in xylem and phloem of a plant transports substances in a ______________ form.
solution
Match the ways water is important for plants with their descriptions:
Transportation = Water transports substances in a solution form Food production = Water combines with carbon dioxide to produce glucose and oxygen Cooling = Water transpires from the surface of leaves, producing a cooling effect
What is the purpose of covering a small, well-watered potted plant with a transparent polythene bag in Activity 3?
to demonstrate transpiration
What is the primary characteristic of a semi-permeable membrane?
Allows only water molecules to pass through
The concentration of sugar molecules is higher in Side A.
False
What is the main difference between Side A and Side B?
Side A contains a dilute sugar solution, whereas Side B contains a concentrated sugar solution.
The semi-permeable membrane has pores of a size that allows _______ molecules to pass through.
water
Match the following components with their descriptions:
Side A = Contains a dilute sugar solution Side B = Contains a concentrated sugar solution Semi-permeable membrane = Allows only water molecules to pass through
What is the direction of water molecules in the diagram?
From Side A to Side B
Sugar molecules can pass through the semi-permeable membrane.
False
What is the purpose of the diagram in the figure?
The diagram illustrates the nature of a semi-permeable membrane.
Study Notes
Root System in Plants
- A plant's root system consists of a main root, lateral roots, and root hairs.
- Root hairs are long extensions of epidermal cells that absorb water and minerals from the soil.
- Root hairs have a rigid cell wall and a selectively permeable cell membrane that allows water and minerals to pass through.
Structure of a Root Hair
- A root hair cell consists of a cell wall, cell membrane, cytoplasm, and nucleus.
- The cell wall is rigid and freely permeable, allowing substances to pass through.
- The cell membrane is selectively permeable, allowing only selected substances to pass through.
Semi-Permeable Membrane
- A semi-permeable membrane allows certain substances to pass through while restricting others.
- Water molecules can pass through the pores of the membrane, but sugar molecules cannot.
Ascent of Sap
- Water absorbed by root hairs enters the xylem and is transported upwards to the stem and leaves.
- This process is called the ascent of sap.
- The ascent of sap is driven by transpiration, which creates a negative pressure that pulls water upwards.
Factors Affecting Transpiration
- Sunlight: Transpiration rate increases during the day when stomata are open.
- Temperature: High temperatures increase the rate of transpiration.
- Wind: Faster wind speeds increase the rate of transpiration.
- Humidity: High humidity reduces the rate of transpiration.
Importance of Transpiration
- Cooling effect: Transpiration helps plants cool themselves by evaporating water.
- Maintaining sap concentration: Transpiration helps maintain the concentration of sap inside the plant body.
Uses of Water in Plants
- Transportation: Water transports substances in a solution form within the plant.
- Food production: Water is used in photosynthesis to produce glucose and oxygen.
- Cooling: Transpiration produces a cooling effect, making the air cooler and more pleasant.
This quiz covers the structure and function of the root system in plants, including the main root, lateral roots, and root hairs.
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