Chapter 8

Question 1

Unicellular

Answer 1

An organism made up of a single cell

Question 2

Multicellular

Answer 2

An organism consisting of more than one cell

Question 3

Internal environment

Answer 3

All the materials contained within the plasma membrane

Question 4

External environment

Answer 4

The environment surrounding a cell outside the plasma membrane

Question 5

Phospholipid bilayer

Hydrophilic head

Answer 5

Hydrophilic head - the ions are charged

Face outwards and can absorb water

Question 6

Phospholipid bilayer

Hydrophobic tail

Answer 6

Hydrophobic tail - non polar (ions are not charged)

Fatty acid tails are hydrophobic which makes them water avoiding and unable to dissolve water

Question 7

Membrane proteins

Adhesion proteins

Answer 7

Link cells together to maintain 3 dimensional structures and the normal functioning of tissues.

Question 8

Membrane proteins

Transport proteins

Answer 8

Act as a passageway that allow specific substances to move across the membrane

Question 9

Membrane proteins

Receptor proteins

Answer 9

Bind hormones and other substances that cause changes to the cells activities

Question 10

Membrane proteins

Recognition proteins

Answer 10

Allow the immune system to identify harmful substances

Question 11

Diffusion

Answer 11

-the movement of molecules across a semi permeable membrane from an area of high concentration to an area of low concentration

• the movement of particles/molecules is called Browian motion
• is passive as it requires no energy
• is moving down the concentration gradient

Question 12

Facilities diffusion

Answer 12

Molecules will spread out over time and move from an area of high concentration to an low concentration

• is passive as it requires no energy
• is moving down the concentration gradient
• uses carrier channels as the molecules are to large or polar (water soluble)

Question 13

Osmosis

Answer 13

The movement of H2O molecules across a semi permeable membrane from an area of low solute concentration to an area of high concentration

-is passive as it requires no energy

Question 14

Endocytosis

Answer 14

Endocytosis – endo means going in
This is an active process, which requires energy to move from vesicles around the cytoplasm and to change the shape of the cell.

• using vesicles to transport materials into the cytoplasm
• this process requires energy

Question 15

Exocytosis

Answer 15

Exocytosis – exo means going out
Is the process by which large molecules held in a vesicle within the cell and are transported to the external environment.

• using a small membrane bound vessel, it is transporting its content out of the cell
• this process requires energy

Question 16

Hypertonic

Answer 16

• low concentration compared to surrounding fluid
• cell shrinks called crenation (animal cell)

Salt sucks water out of cell

Question 17

Hypotonic

Answer 17

-High concentration compared to surrounding fluid
-cell expands called haemolysis (animal cell) and explodes
-cell expands called turgid (plant cell)
SALT SUCKS WATER INTO CELL

Question 18

Isotonic

Answer 18

Same concentration compared to surrounding fluid