3 Movement in and out of cells

Question 1

Define diffusion

Answer 1

the net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, as a result of their random movement

Question 2

Where does the energy for diffusion come from?

Answer 2

kinetic energy from the random movement of molecules and ions

Question 3

Importance of diffusion of gases and solutes in living organisms

Answer 3

• helps plants get rid of waste products like oxygen during photosynthesis
• helps in gas exchange during respiration in plants and animals

Question 4

Roles of water (M TED)

Answer 4

• as a solvent for metabolic reactions to take place
• plasma contains a lot of water for glucose to dissolve in it
• kidneys excrete urea out of the body, urea dissolves in water to form urine
• needed to dissolve nutrients and enzymes in the alimentary canal during digestion

Question 5

Define osmosis

Answer 5

net movement of water molecules from a solution of higher water potential to a solution of lower water potential, through a partially permeable membrane

Question 6

What happens to an animal cell placed in a hypertonic solution?

Answer 6

• water leaves cells
• cytoplasm shrinks and cell shrivels up

Question 7

What happens to an animal cell placed in a hypotonic solution?

Answer 7

• water enters cell
• cell membrane stretches until cell bursts

Question 8

What happens to a plant animal placed in a hypertonic solution?

Answer 8

• water leaves cell
• cell shrinks and becomes flaccid
• cell membrane pulls away from cell wall and cell becomes plasmolyzed

Question 9

What happens to a plant cell placed in a hypotonic solution?

Answer 9

• water enters cell
• cytoplasm and vacuoles swells
• strong cell wall prevents bursting, cell becomes turgid due to turgor pressure

Question 10

Define active transport

Answer 10

the process in which particles are transported across a biological membrane, from a region of lower conc. to a region of higher conc, against a conc. gradient, with the use of energy from respiration

Question 11

What moves molecules and ions across a membrane during active transport?

Answer 11

protein carriers

Question 12

Importance of turgor in plants

Answer 12

• maintains shape of soft tissues in plants
• keeps most leaves and young stems erect due to turgor pressure within the cells
• keeps non-woody plants firm and upright
• turgor in guard cells cause stomata to remain open during the day. Lack of turgor in guard cells cause stomata to close at night