CH 6 : PLANT NUTRITION

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Questions and Answers

What role does starch play in plants after photosynthesis?

Long-term energy storage (correct)

Transport molecule in phloem

Immediate energy source

Structural component of cell walls

Which substance is formed first during photosynthesis?

Fructose

Sucrose

Glucose (correct)

Lactose

What is the primary function of cellulose in plant cells?

Formation of cell walls (correct)

Nectar production

Transport in phloem

Energy storage

What do nitrate ions contribute to plant biology?

Formation of amino acids Signup and view all the answers

Which factor is NOT considered a limiting factor for photosynthesis?

Chlorophyll concentration Signup and view all the answers

Which process is essential for transporting sucrose in plants?

Phloem transport Signup and view all the answers

In what conditions do plants primarily exchange gases?

During the day and night Signup and view all the answers

What is the primary energy source for photosynthesis?

Light energy Signup and view all the answers

What is the main importance of photosynthesis for living organisms?

It is the main source of oxygen for aerobic respiration. Signup and view all the answers

Which function of the leaf cuticle helps with water retention?

It prevents water evaporation from the leaf. Signup and view all the answers

Why are palisade cells packed with chloroplasts?

To absorb the maximum amount of light possible. Signup and view all the answers

How do the spatial arrangements of palisade cells benefit photosynthesis?

They are oriented vertically to maximize light capture. Signup and view all the answers

What characteristic of palisade cells helps them to obtain carbon dioxide and water efficiently?

Elongated shape. Signup and view all the answers

In addition to trapping sunlight, what other role does chlorophyll play in photosynthesis?

It traps the energy of sunlight. Signup and view all the answers

Which layer of the leaf primarily acts as a barrier against pathogens?

Cuticle layer. Signup and view all the answers

What is the role of the upper epidermis in leaf structure?

It secretes cuticle and serves as a barrier. Signup and view all the answers

What happens at the compensation point in a plant?

Oxygen produced equals oxygen needed for respiration. Signup and view all the answers

Which of the following is NOT a necessary condition for photosynthesis?

Darkness Signup and view all the answers

Which factor is considered an external limiting factor affecting the rate of photosynthesis?

Light intensity Signup and view all the answers

What is a common consequence of a deficiency in nitrate ions for plants?

Stunted growth rate Signup and view all the answers

Which action can increase soil fertility?

Adding artificial fertilizers Signup and view all the answers

How do plants primarily absorb mineral salts from the soil?

Active transport through roots Signup and view all the answers

Which internal limiting factor affects photosynthesis?

Surface area of the leaf Signup and view all the answers

What is the role of leguminous plants in soil fertility?

They harbor bacteria that fix nitrogen. Signup and view all the answers

What is the primary function of spongy tissue in leaves?

To help in photosynthesis by allowing gas circulation Signup and view all the answers

What purpose does the xylem serve in the leaf's vascular bundle?

To transport water and minerals to cells Signup and view all the answers

Why are there more stomata in the lower epidermis than in the upper epidermis of a leaf?

It helps in gas exchange without losing too much water. Signup and view all the answers

What is the role of guard cells surrounding each stoma?

To regulate the opening and closing of stomata Signup and view all the answers

During photosynthesis, what gas is released as a waste product?

Oxygen Signup and view all the answers

Which statement is true regarding the relation between photosynthesis and respiration in plants?

Photosynthesis occurs under bright light while respiration occurs both day and night. Signup and view all the answers

What is the first step in the process of photosynthesis?

Diffusion of carbon dioxide through stomata Signup and view all the answers

Which component is responsible for trapping light energy during photosynthesis?

Chlorophyll in chloroplasts Signup and view all the answers

What is the primary role of magnesium in plants?

To synthesize chlorophyll Signup and view all the answers

What happens when a plant's chlorophyll is absent?

The plant exhibits yellow leaves Signup and view all the answers

What is the main consequence of excessive use of fertilizers in aquatic environments?

Stimulation of algae growth Signup and view all the answers

Which step is NOT involved in the destarching process of a plant?

Allowing the plant to transport water efficiently Signup and view all the answers

What does a color change to dark blue or blue-black indicate after iodine solution is added?

Presence of starch in the leaf Signup and view all the answers

During the iodine test, which procedure helps to remove chlorophyll from the leaf?

Heating the leaf in a water bath with alcohol Signup and view all the answers

What is the result of decreased oxygen concentration in water caused by decomposing dead plants?

Death of aerobic organisms Signup and view all the answers

What is the first step in testing for starch in a plant leaf?

Boiling the leaf in water Signup and view all the answers

What is the purpose of exposing the destarched variegated leaf to light in the experiment?

To observe if chlorophyll is essential for photosynthesis Signup and view all the answers

What color indicates the presence of starch in the leaf after iodine testing?

Blue-black Signup and view all the answers

In the experiment involving light, what was the main observation made after exposing the plant to light?

The exposed parts gained a dark blue color Signup and view all the answers

Which procedure was used to demonstrate that carbon dioxide is necessary for photosynthesis?

Placing a leaf in a flask with soda lime Signup and view all the answers

What is the main conclusion drawn from the experiment with the destarched plant and light?

Light, chlorophyll, and carbon dioxide are all necessary for photosynthesis Signup and view all the answers

What role does destarching play in the experiments conducted?

It ensures that any positive result is due to the experiment and not stored starch Signup and view all the answers

What is inferred from attempting to detect starch in the leaf placed in potassium hydroxide?

The leaf was unable to photosynthesize due to lack of carbon dioxide Signup and view all the answers

How does chlorophyll affect the color change observed in the leaf during starch testing?

It absorbs light needed for photosynthesis, which then shows the color Signup and view all the answers

Study Notes

Plant Nutrition

Plants use carbohydrates produced during photosynthesis for energy storage (starch) and building cell walls (cellulose). Glucose is also used in respiration to provide energy, and sucrose is transported through the phloem. Nectar is used to attract insects for pollination.
Nitrate ions are crucial for making amino acids, while magnesium ions are essential for chlorophyll production.
Photosynthesis requires chlorophyll, light, and carbon dioxide. Investigate the effects of varying light intensity, carbon dioxide concentration, and temperature on photosynthesis's rate. Explore gas exchange reactions in aquatic plants using a hydrogen carbonate indicator solution.
Leaf structure is adapted for photosynthesis. Most leaves have a large surface area and are thin, facilitating maximum light absorption and gas exchange.
Photosynthesis is the process where plants use raw materials (carbon dioxide and water) and light energy to create carbohydrates. Chlorophyll traps light energy and converts it into a chemical form, powering the process. Crucially, glucose is formed initially, then transformed into starch for storage, cellulose for cell walls, or used in respiration.

Importance of Photosynthesis

Photosynthesis is the primary source of oxygen for all living organisms.
It's the fundamental energy source for almost all living things.
It regulates the balance of carbon dioxide and oxygen in the atmosphere.
Photosynthesis is responsible for the energy stored in fossil fuels (coal and petroleum).

Leaf Structure and Function

A leaf's structure (e.g., large surface area, thinness) is essential for its function in photosynthesis.
The cuticle prevents water loss.
Epidermis layers protect the leaf.
Palisade mesophyll cells are packed with chloroplasts for maximum light absorption.
Spongy mesophyll tissue contains air spaces for gas exchange.
Vascular bundles (xylem and phloem) transport water and nutrients, respectively.
Stomata allow gas exchange.
Guard cells regulate the opening and closing of stomata.

Photosynthesis Process

Carbon dioxide enters the leaf through stomata.
Water is absorbed from the soil and transported to the leaf via xylem.
Chlorophyll in chloroplasts traps light energy.
Light energy converts carbon dioxide and water into glucose.
Oxygen is released as a byproduct.

Relationship Between Photosynthesis and Respiration

Plant respiration occurs continuously. Photosynthesis's rate is higher under bright light.
When photosynthesis's rate equals respiration's rate, there is no net gas exchange. This equilibrium point is known as the compensation point.

Factors Affecting Photosynthesis Rate

External factors (light intensity, carbon dioxide concentration, and temperature).
Internal factors (number of stomata, chloroplasts, and leaf surface area).

Limiting Factors

A limiting factor is a substance in short supply that restricts an aspect of growth or another process (like photosynthesis).
In low light or CO2 levels, light or CO2, respectively, become the limiting factor.

Mineral Requirements for Plant Growth

Plants need mineral salts, including nitrates and magnesium, for healthy growth. Nitrate is needed to make amino acids and proteins. Magnesium is vital for chlorophyll production.

Soil Fertility Enhancement

Adding fertilizers, applying manure, and growing legumes improves soil fertility.
Legumes promote nitrogen fixation by bacteria in the soil.

Eutrophication

Excessive nutrient runoff (mostly nitrates and phosphates) into water bodies causes eutrophication.
This process stimulates excessive algae growth, depleting oxygen and harming aquatic life.

Practical Work: Destarching Plants and Testing for Starch

Procedures for destarching a plant and testing for starch in plant leaves.
Iodine solution is used to test for starch presence (dark blue/black color indicates starch).

Practical Work: Light and Photosynthesis

Experiment to demonstrate the importance of light for photosynthesis.
Covered and uncovered leaf portions are analyzed for starch presence.

Practical Work: Carbon Dioxide and Photosynthesis

Experiment to show the need for carbon dioxide in photosynthesis.
Leaves exposed to CO2-deficient environments versus controlled environments are analyzed for starch.

Practical Work: Oxygen Evolution During Photosynthesis

Setup and observations with hydrogen carbonate solution to show oxygen evolution via photosynthesis.

Practical Work: The Effect of Light Intensity on Photosynthesis

Procedures and observations are conducted to show the relationship between photosynthetic rate and light intensity.

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Description

Test your knowledge on the essential processes of photosynthesis and the important roles of various substances in plants. This quiz covers topics such as the functions of starch and cellulose, gas exchange, and the characteristics of leaf structures. Prepare to dive into the fascinating world of plant biology!