Long Answer Question 4

Question 1

What is the plasma membranes function in monitoring molecule movement? (2)

Answer 1

• The plasma membrane regulates the molecules coming in and out of a cell
• It is known as selectively permeable because only certain molecules may move in and out. There are several different ways molecules can enter and exit cells.

Question 2

What is diffusion?

Answer 2

Diffusion is a type of molecule movement where lipid soluble molecules and gases move towards the area of lower concentration. Does not require energy.

Question 3

• What is osmosis?

- What are solutions classified as when cells are placed in them and how the cells react in these solutions? (4)

Answer 3

• Osmosis is the diffusion of water towards areas of lower concentration. Does not require energy.
• Solutions are classified as one of the three when cells are placed in them: hypertonic, hypotonic, and isotonic.
• Hypertonic solutions are solutions where the solute concentration outside the cell is greater than the solute concentration inside the cell. This causes water to exit the cell and the cell to shrink. In a hypertonic solution, the shrivelling of the cell is known as crenation.
• Hypotonic solutions are the opposite and cause water to enter the cell and the cell to swell. In a hypotonic solution, the bursting of a swollen cell is called cytolysis.
• Isotonic solutions are solutions where the solute concentration is equal inside and outside the cell. This means the net movement of water is zero.

Question 4

What is facilitated transport? (2)

Answer 4

• Non-lipid-soluble molecules such as sugars and some amino acids are transported across the plasma membrane towards the area of lower concentration by facilitated transport. Does not require energy
• Carrier protein speeds rate at which the solute passes the plasma membrane, carrier protein changes shape as it moves solute across the membrane

Question 5

Why is water important for osmosis?

Answer 5

Water is important because it can cross cell membrane, allowing process of osmosis to regulate salt and water balance (osmotic balance) across membrane.

Question 6

What is active transport?

Answer 6

• Active transport is the movement of sugars, amino acids, and ions towards an area of higher concentration. This is accomplished through the use of a carrier protein and requires energy (usually in the form of ATP)

Question 7

What is membrane-assisted transport or vesicle formation?

Answer 7

• A way to transport macromolecules into and out of the cell, membrane is needed to form the vesicle. Requires an expenditure of energy but vesicle membrane contains macromolecule from mixing with other molecules in cytoplasm

Question 8

What is exocytosis?

Answer 8

• Exocytosis is the use of a vesicle to move macromolecules out of a cell. These vesicles fuse with the plasma membrane and contribute to cell growth. Requires an expenditure of energy

Question 9

• What is endocytosis?

- What are the three types of of endocytosis?

Answer 9

• Endocytosis is the formation of vesicles using the plasma membrane in order to move macromolecules into the cell. Requires an expenditure of energy
• Phagocytosis is a type of endocytosis that transports large substances like food into the cell.
• Pinocytosis is a type of endocytosis that transports liquids or very small particles into the cell. Pinocytosis occurs almost continuously.
• Receptor mediated endocytosis is a form of pinocytosis that uses receptor proteins to bind to specific molecule like vitamins or peptide hormones. These receptor proteins either migrate to the coated pit that forms into the vesicle or they are already inside the pit.

Question 10

How is water needed to get nutrients into body cell? (2)

Answer 10

• Digestive enzymes speed up the chemical reactions that involve digestion of the components of food. They are digested to form appropriate nutrient molecules that can be absorbed into the cells
• Water is a huge part of digestive enzymes because the digestion process requires a hydrolysis reaction - a reaction to degrade polymers where the components of water are added
  Summary: Big pieces of food are unable to enter the body cells, the digestive enzymes use the hydrolysis reaction to break down food in useable nutrients for cells

Question 11

What are the main subtopics for this question? (10)

Answer 11

• function of plasma membrane
• diffusion definition
• osmosis definition and osmosis in different solutions
• the importance of water in osmosis
• facilitated transport definition
• active transport defintion
• vesicle formation/ membrane-assisted transport definition
• exocytosis defintion
• endocytosis definition and different types of endocytosis
• requirement of water to get nutrients into body cell