Flashcard Biology unit 3 | Quizlet

Diffusion

movement of molecules from a region of high concentration to a region of lower concentration

concentration gradient

The difference in concentration of a substance between two regions

role of cell membrane in diffusion

It restricts the free movement of molecules and acts as a partially permeable membrane.

What is a partially permeable membrane?

A membrane that allows some molecules to cross easily, but others with difficulty or not at all.

What are the benefits of diffusion for living organisms?

It helps them obtain many of their requirements, get rid of waste products, and carry out gas exchange for respiration.

substances that organisms get by diffusion

Oxygen, carbon dioxide, and other nutrients.

why is oxygen needed in plants?

respiration

why is carbon dioxide needed in plants?

photosynthesis

Brownian motion

random movement of particles

Where does the energy for diffusion come?

kinetic energy of random movement

Factors that influence diffusion

Temperature, concentration gradient, surface area, and distance.

Temperature increases

rate of reaction increases

concentration gradient increases

rate of reaction increases

rate of diffusion increases

rate of reaction increases

distance increases

rate of reaction decreases

water importance

it dissolves many substances (solvent)

Osmosis

diffusion of water molecules from high water potential to a low water potential through a partially permeable membrane

water moves into plant cell

vacuole gets bigger, pushes the cell membrane against the wall, it makes the cell rigid, it becomes strong

pressure created by cell wall

stops too much water from coming in and bursting. It increases turgor pressure.

if plants don't get enough water

they wilt

active transport

movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

Why is energy needed for active transport?

because it goes against the concentration gradient.

Importance of active transport

protein carrier, uptake of glucose, uptake of ions