Plant structure and function, Biodiversity and Conservation

Plant structure and function, Biodiversity and Conservation

What type of organisms are plants and animals classified as?

Eukaryotes

What do plant and animal cells have in common?

Both have many membranes, cytoplasm, and a nucleus. They also have rough and smooth endoplasmic reticulum, an active Golgi apparatus, and mitochondria to produce ATP.

What is the main function of mitochondria in both plant and animal cells?

Mitochondria produce ATP, which is essential for the functioning of both plant and animal cells

What are some organelles found in plant cells but not in animal cells?

Plant cells contain organelles like chloroplasts, large central vacuoles, and a cellulose cell wall.

What gives plant cells their regular shape and strength?

The cell wall, which is made mostly of cellulose, provides strength and support.

What is the primary material that makes up the plant cell wall?

The plant cell wall is mostly made of insoluble cellulose.

What is the function of the cell wall in plant cells?

The cell wall gives strength, structure, and support to the plant cell. It also regulates the permeability to substances dissolved in water.

What is added to the plant cell wall in cork tissues?

Suberin is added to the cell wall in cork tissues, reducing permeability.

What compound is part of the cell wall in wood?

Lignin is added to the cell wall structure in wood, making it more rigid and less permeable.

What is the middle lamella and what is its function?

The middle lamella is the first layer of the plant cell wall that is formed when a plant cell divides. It is made of pectin, which holds adjacent plant cells together.

What is pectin and how does it contribute to the cell wall?

Pectin is a polysaccharide with negatively charged carboxylate groups that combine with calcium ions to form calcium pectate, binding adjacent cells together.

What is the primary cell wall?

The primary cell wall is the flexible outer layer of a plant cell that is formed initially. It has cellulose microfibrils arranged in a similar direction.

What causes the secondary cell wall to form?

As the plant ages, the secondary cell wall develops, with densely packed cellulose microfibrils arranged at different angles, increasing rigidity.

What additional substances may be added to the secondary cell wall?

Hemicelluloses may harden the wall further, and lignin may be added, particularly in woody perennials, making the wall even more rigid.

What are plant fibers, and where are they found in plant structures?

Plant fibers are long cells with heavily lignified cellulose walls, found in various parts of plants. They are used in products like clothing, building materials, ropes, and paper.

What is cellulose?

Cellulose is a complex carbohydrate that is the main component of plant cell walls.

What are cellulose, starch, and glycogen all similar in?

They are all complex carbohydrates consisting of long chains of glucose molecules.

How are the glucose molecules in cellulose connected?

The glucose molecules in cellulose are joined by glycosidic bonds.

What are the two isomers of glucose ?

The two isomers of glucose in cellulose are alpha-glucose and beta-glucose.

How do alpha-glucose and beta-glucose differ from each other?

They differ in the arrangement of atoms on the side chains of the glucose molecules.

How does the isomer of glucose affect the bonds in starch and cellulose?

The different isomers (alpha-glucose and beta-glucose) form different bonds, which influences the type of polymers they create.

What is the difference in the glucose units used in starch and cellulose?

Starch uses alpha-glucose, while cellulose uses beta-glucose.

What type of glycosidic bond links glucose molecules in cellulose?

In cellulose, the glucose molecules are linked by 1,4-glycosidic bonds, where one monomer is inverted for bonding to occur.

How does the inversion of glucose in cellulose affect the molecule?

The inversion of glucose causes the hydroxyl (-OH) groups to stick out on both sides of the molecule, allowing for hydrogen bonding.

What is cross-linking in cellulose?

Cross-linking occurs when hydrogen bonds form between the partially positively charged hydrogen atoms of the hydroxyl groups and the partially negatively charged oxygen atoms in nearby glucose molecules, holding neighboring chains together.

What gives cellulose its considerable strength?

The hydrogen bonds between cellulose molecules.

How do cellulose molecules differ from starch molecules in terms of structure?

Cellulose molecules are long and straight, while starch molecules form compact globular structures.

Why is starch important as an energy source for animals?

Starch is a primary energy source in the diet of many animals due to its ability to be broken down into glucose.

Why can't most animals digest cellulose?

Most animals lack the enzymes to break the 1,4-glycosidic bonds between B-glucose molecules in cellulose.

Which animals can digest cellulose and how?

Ruminant animals use enzymes from bacteria in their gut, and termites use enzymes from protozoa.

Why is cellulose important in the human diet, despite not being digestible?

Cellulose acts as roughage or fiber, which is essential for digestive health.

What are cellulose microfibrils and what is their role in plant cell walls?

Cellulose microfibrils are groups of 10,000-100,000 cellulose molecules that form a strong structure in the plant cell wall.

What binds the cellulose microfibrils together in the plant cell wall?

A matrix of hemicelluloses and other short-chain carbohydrates like mannose, xylose, and arabinose.

What is the function of the cellulose matrix in plant cell walls?

It creates a composite material that provides strength and flexibility to the plant, supporting its vertical structure while allowing it to wilt when water is scarce.

What are plasmodesmata and what is their function?

Plasmodesmata are cytoplasmic bridges that allow material exchange between plant cells.

How do plasmodesmata form between plant cells?

Plasmodesmata form when cells divide, leaving threads of cytoplasm connecting the two cells through gaps in the cell wall.

What is the symplast?

The interconnected cytoplasm of adjacent plant cells, connected by plasmodesmata.

What happens to cell walls during secondary thickening?

Hemicelluloses and lignin are deposited, making the wall thicker, except in the areas around plasmodesmata where pits are left.

What is the role of pits in the xylem?

Pits allow water to move between xylem vessels, maintaining water flow at consistent pressure.

What role do plasmodesmata play in plant grafting?

Plasmodesmata are crucial for communication between grafted tissues, allowing cell division and growth to begin after the graft tissue connects to the host tissue.

what are pits ?

area of unthickened cell wall which allows

the flow of water and dissolved minerals

between xylem cells

What are some differences and similarities between plant and animal cells ?

They are similar to each other with their cytoplasm, nucleus, mitochondria, ribosomes, endoplasmic reticulum and more. But they can also be very different as plant cells may contain several kinds of organells that are not found in animal cells which these include Permanent vacuole, chloroplasts. Cell wall is not an organelle but it’s something that plant cells have and animal cells don’t.

What is a vacuole?

A vacuole is any fluid-filled space inside the cytoplasm which is surrounded by a membrane.

What is the difference between animal cells’ vacuole and plant cells’ vacuole?

vacuoles occur quite frequently in animal cells, but they are only temporary, being crested and destroyed when needed. In not woody plant cells, the vacuole is a permanent structure with an important role.

What is the important role of vacuole in non-woody plant cells?

The vacuole can occupy up to 80 percent of the volume of a plant cell.

What is tonoplast ?

Tonoplast is a specialised membrane surrounding the vacuole in plant cells.

Everything about Tonoplast

Tonoplast contains many different many different protein channels and carrier systems. It controls the movement of substances into and out of the vacuole and so it controls the water potential of the cell.

What is vacuole filled with ?

The vacuole is filled with cell sap.

Everything about the cell sap

The cell sap which fills the vacuole is a solution of various substances in water. This solution causes water to move into the cell by osmosis and this means that the cytoplasm is kept pressed against the cell wall. This keeps the cell turgid (swollen) and the whole plant stays upright. The pressure that can be that can be developed in this way are very large indeed. The pressure in a leaf cell can be up to 1500 kpa - in contrast, the pressure in a human artery when the heart is pumping blood out into the body is only 16 kpa