Leaf Structure and Function

What are the reactants of photosynthesis?

6 Carbon dioxide, water and light energy

What is the equation for photosynthesis?

6CO2 + 6H2O + light energy = C6H12O6 + 6O2

What factors regulates the opening and closing of stoma?

Guard cells are what regulate the opening and closing, they are surrounded by each stoma

During what stage of photosynthesis is O2 produced?

Light dependent reactions

Describe the layers and parts of the chloroplast.

The chloroplasts is made up of an outer membrane then an inner membrane. Within the inner membrane is granum which are stacks of thylakoids surrounded by stroma, the cytoplasm of a chloroplast

How many turns of the calvin cycle does it take to create one glucose?

6

What gas enters a plant and what gas is released?

Carbon dioxide, oxygen

Name the two pigments or light absorbing compounds found within thylakoid membranes.

Chlorophyll a, Chlorophyll b (Carotene), Carotenoids (Xanthophyll)

Where does photosynthesis occur?

Chloroplasts

Describe how the structure of a leaf is optimized for light absorption.

Due the leaves being the highest point of the plant is is easier for leaves to be fully exposed to sunlight

Describe the process of the light reaction.

First water is broken up the hydrogen being used to create the gradient and dioxide is released as a waste product. 2 electrons are used to replace the ones that are lost from breaking the water bonds. Light energy then is absorbed by PS2 or photosystem two, the light excites the electrons and 2 escape from the chlorophyll which are captured by the electron acceptor 2. It then releases these electrons through the electron transport chain so it can be dropped off at the PS1 so it can collect more electrons. Photosystem 1 then releases the electrons to electron transport 1 so it can replace it's lost electrons. The electron acceptor 1 then releases it's electrons to NADPH so it can collect more electrons.

What are the products of photosynthesis?

Glucose and oxygen

Which region of the visible light spectrum is not absorbed well by chlorophyll?

Green light because it is refracted from the plant making it difficult to be absorbed

What is the vein or vascular bundle?

In plants, a cluster of vascular tissue in leaves

What is a bundle sheath?

Is a stiff layer of cells that regulates movement of substances between tissues to protect the vein

What is the palisade mesophyll?

Layer of tall column-shaped mesophyll cells where the majority of photosynthesis takes place due to the amount of light its cells absorb

What is the upper epidermis of a plant?

Layer under the cuticle of a plant; first layer of cells that protects the cell from pathogens

Why do leaves change color in the fall?

Leaves change color due to the availability of water which is restricted as the temperature gets colder and the amount of sunlight which may also be restricted due to less sun and shorter days

Explain the general photosynthesis process.

Light energy and water enters the light dependent reactions along with ADP + D NADP+ from the Calvin Cycle. The water is released from the light dependent reactions and become dioxide. The NADP+ is then turned into NADPH and then renters the Calvin cycle as well as ADP + D becoming ATP which also enters the Calvin cycle. The molecules that enter the Calvin cycle without the light dependent reactions is carbon dioxide which is released and combined into the molecule known as glucose which is stored as stable energy

What are the two steps of photosynthesis?

Light reaction (light dependent reaction) and the Calvin Cycle (light independent reaction)

What is the spongy mesophyll?

Loose tissue with many air spaces between it's cells. They have irregular cells causing pockets which contain carbon dioxide and oxygen

What is the chloroplast?

Membrane organelle that contains both structures and enzymes necessary for converting light energy into glucose

What is the lower epidermis of plant?

Outer layer of a plant, under layer of the cells that protects the cell from pathogens

What is the stoma?

Pore-like openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse in and out of the leaf that allows carbon dioxide and oxygen to diffuse in and out of the leaf with turgor pressure

What is chlorophyll a?

Primary photosynthetic pigment of all plants, it's located at the reaction center of photosystems

What is the cuticle of a plant?

Protecting waxy, lipid layer over the top of the plant that protects against water loss (water travels down the lipid layer and falls down to the roots)

What is chlorophyll b and carotenoids?

Secondary pigments that capture light energy and transfer it to chlorophyll a at the reaction center

What are guard cells?

Specialized cells in the epidermis that control the opening and closing of the stoma by responding to changes in water pressure

Describe the layers of a leaf in order.

The leaf begins with the cuticle, the upper epidermis, the palisade mesophyll, the spongy mesophyll. Among the spongy mesophyll is a vascular bundle or vein which is made up of the xylem and phloem. After spongy mesophyll, is the lower epidermis where the stoma is located with guard cells within them.

What factors regulates the opening and closing of stomata?

The temperature, the amount of moisture in the air

Are stoma likely to be open or closed on a hot day?

They are likely to be closed because the stoma collects lots of water which could evaporate on a hot day

The leaves of desert plants often have two or more layers of palisade mesophyll, rather than the single layer that is a characteristic of most leaves. How might this modified structure be advantageous to a desert plant?

This allows for them to go without water for a long while because the two layers provide a "protection" for the water source not to be evaporated as easily as other plants with one palisade mesophyll layer

What is the light reaction?

This is the name for the light dependent chemical process where ATP and NADPH (useable energy) are formed in the thylakoid membrane

What is the calvin cycle?

This is the name for the light indepedent chemical process which occurs in the stroma. ATP and NADPH are not stable so plants use carbon dioxide to create glucose, which can be stored

The pigment molecules responsible for photosynthesis are located where?

Thylakoid membranes of the chloroplasts

What is the phloem?

Vascular tissue responsible for the transport of nutrients throughout the plant

What is the xylem?

Vascular tissue that carries water upward from the roots to every part of the plant