2.1.6 - Eukaryotic cells 4

Question 1

what is a vacuole?

Answer 1

any fluid-filled space inside the cytoplasm surrounded by a membrane

Question 2

what is a tonoplast?

Answer 2

the specialised membrane that surrounds the permanent vacuole in plant cells and controls movements of substances into and out of the cell sap

Question 3

what is the main function of the tonoplast?

Answer 3

to control the water potential of the cell

Question 4

what does the tonoplast have that helps it with its function?

Answer 4

• protein channels
• carrier systems
  (it controls movement of substances)

Question 5

what is cell sap?

Answer 5

the aqueous solution that fills the permanent vacuole

Question 6

what does the cell sap do?

Answer 6

• the solution causes water to move into the cell by osmosis
• result = cytoplasm is kept pressed against the cell wall
• keeps the cell turgid + whole plant upright
  (note: this pressure is very high)

Question 7

define osmosis

Answer 7

specialised form of diffusion that involves the movement of solvent molecules down a concentration gradient through a partially permeable membrane

Question 8

Other than to keep the structure of the cell and plant, what role do vacuoles play within the cell?

Answer 8

• to store substances (e.g protein, waste products, pigments etc..)
• e.g betacyanin pigment in beetroot
• won’t leak into cytoplasm unless cut
• or heated as this changes the shape of the vacuole membrane

Question 9

Overall, what are the two key structures in the support systems of plants?

Answer 9

• tonoplast

- permanent vacuole

Question 10

define chloroplasts

Answer 10

an organelle adapted to carry out photosynthesis, containing the green pigment chlorophyll

Question 11

Why are chloroplasts so important to plant cells?

Answer 11

• they enable the plant to make their own food
• through photosynthesis

(note: only the green parts of the plant will actually contain chloroplasts but all plant cells have the genetic information to make chloroplast)

Question 12

What are the similarities between mitochondria and chloroplast?

Answer 12

• large organelles with biconvex shape
• contain their own DNA
• surrounded by outer membrane
• folded inner membrane to increase surface area
• both part of the endosymbiotic theory

Question 13

What separates chloroplast from mitochondria?

Answer 13

• site of photosynthesis
• contain chlorophyll (used to trap energy from light)
• formed from unspecialised plant organelle (leucoplast)

Question 14

define chlorophyll

Answer 14

the green pigment largely responsible for trapping energy from light, making it available for the plant to use in photosynthesis

Question 15

what are amyloplasts?

Answer 15

plant organelles that store starch

also develop from leucoplasts

Question 16

Where are amyloplasts found?

Answer 16

in areas of a plant that store starch

also in large numbers

Question 17

Why do amyloplasts store starch?

Answer 17

so the plant can convert it into glucose to provide energy when needed.