Topic 1

Question 1

What is a Eukaryotic Cell

Answer 1

Animal and plant cells are examples

Contain- cell membrane, cytoplasm, DNA in nucleus

Question 2

What is a Prokaryotic cell

Answer 2

They are bacteria- single celled organisms
0.2-2 um
May also contain extra ring of DNA called plasmids (no DNA in nucleus)
contain - cytoplasm, cell membrane surrounded by a cell wall

Question 3

Function of Cytoplasm

Answer 3

A jelly-like material that contains dissolved nutrients and salts and structures called organelles. It is where many of the chemical reactions happen

Question 4

Function of Nucleus

Answer 4

Contains genetic material, including DNA, which controls the cell’s activities

Question 5

Cell membrane

Answer 5

It is permeable to some substances but not to others and so controls the movement of substances in and out of the cell

Question 6

Mitochondria

Answer 6

Organelles that contains the enzymes for respiration, and where most energy is released in respiration

Question 7

Ribosomes

Answer 7

Tiny structures where protein synthesis occurs

Question 8

Chloroplast
Cell wall
Permanent vacuole

Answer 8

Organelles that contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis. Contains the enzymes needed for photosynthesis

Made from cellulose fibres and strengthens the cell and supports the plant

Filled with cell sap to help keep the cell turgid

Question 9

Structure and Function of Nerve cells

Answer 9

They are specialised to carry electrical impulses around the body of an animal. Adaptations include:

Lots of dendrites for connections to other cells
Axons to carry impulse to one place to another
Synapses (nerve endings) are adapted to pass implies to another cells or muscles using transmitter chemicals, contain lots of mitochondria to provide energy for ‘Trans Chems’

Question 10

Structure and Function of Muscle cells:

Answer 10

Muscle cells are specialized to contract and relax. Striated muscles work together in tissues called muscles. Adaptations include:

Special proteins that slide over each other to make fibres contract
Lot of mitochondria for energy to contract and relax
Can store glycogen- to be broken for respiration

Question 11

Structure and Function of Sperm Cells:

Answer 11

Long tail to help move
Mid section filled with mitochondria, energy for tail to work
Acrosome- stores digestive enzymes which break outer layer of egg
Large nucleus- genetic info to be passed on

Question 12

Structure and Function of Root Hair Cells:

Answer 12

Root hair cells help take in water more efficiently. They are close to xylem tissue. The xylem tissues carry the water and mineral ions up to the plant. They are moved into the root hair cell via active transport..

Adaptations include:

Large surface area for more water to move into cell
Large permanent vacuole- speeds up water movement from soil across the hair cell
Lots of Mitochondria that transfer energy needed for active transport into hair cell

Question 13

Structure and Function of Xylem Cells:

Answer 13

Are the transport tissue in plant cells that carry water from roots to leaves and shoots. Adaptations include:

They lose their end walls so the xylem forms a continuous, hollow tube. This hollow tube makes it easier for water ions to pass through
They become strengthened by a substance called lignin. Lignin gives strength and support to the plant

Question 14

Structure and Function of Phloem Cells:

Answer 14

Carry food made by photosynthesis around the body of the plant. The dissolved food can go up and down the tube

Between cell walls there are sieve plates. These allow the water dissolved food solution to move freely up and down.
Companion cells ro help support the structure

Question 15

Use of Cell differentiation, difference in Plants and animals

Answer 15

Plants: Can differentiate throughout their lifetime

Animals:

• Cells differentiate at early age then cannot again
• Are replaced by adult stem cells (retain ability to undergo differentiation)
• For growth + repair

Question 16

Compare light microscopes and electron microscopes (4m)

Answer 16

Light microscopes- using beam of light (2D)
Very cheap + used anywhere
Used to look at cells + magnify live specimens
X2000 magnification

Electron microscope- using beam of electrons to form image (3D)
Large, expensive
Used to look at structures inside cells
X2,000,000 magnification

Question 17

Diffusion definition
Factors effecting Diffusion
Adaptations of diffusion

Answer 17

Diffusion- is the net movement of a substance from an area of high concentration to low concentration

Concentration gradient - a larger difference in the high and low concentrations increases the diffusion rate.

Temperature - a higher temperature provides the particles with more kinetic energy increasing the diffusion rate.

Surface area - a larger surface area through which diffusion can happen increases the diffusion rate.

having a large surface area
a membrane that is thin, to provide a short diffusion path
(in animals) having an efficient blood supply
(in animals, for gaseous exchange) being ventilated.

Question 18

Diffusion in respiration

Answer 18

1) The oxygen we need for respiration passes from the air in your lungs to RBC through the cell membranes by diffusion
2) Oxygen also then moves by diffusion (down the conc. gradient) from blood cells the cells of our body where it is needed.

3) CO2 also moves out from the body cells → RBC → air in lungs by diffusion
(Diffusion of oxygen and CO2 for example in the opposite direction is known as gas exchange)

4) Cell membrane is adapted to increase rate of diffusion by having a large surface area

Question 19

Define Osmosis

Examples of water in solution

Answer 19

Osmosis- The net movement of water particles from an area of high concentration to low concentration through a partially permeable membrane. This follows the concentration gradient

EXAMPLE- HYPERTONIC
If a cell uses up water in chem reaction, the cytoplasm becomes more concentrated… The surrounding fluid becomes hypotonic to the cell and more water immediately moves in by osmosis

EXAMPLE- ISOTONIC
If cytoplasm is too dilute because of excess water, surrounding fluid becomes hypertonic. The cell is now isotonic to solution (equilibrium is reached )

EXAMPLE- HYPOTONIC
When too much water is on outside. The cell undergoes osmosis but when there is too much the cell is at risk of bursting.

Question 20

Active transport definition and energy

Answer 20

Active transport is the net movement of particles against a concentration gradient. Energy is therefore required. During active transport, molecules are transported from a low concentration to a high concentration

Active transport means that cells can absorb ions from a very dilute solution. It enables the cell to move substances from one place to another

It needs energy. This energy is released from cell respiration. Cells involved usually have many mitochondria to release the energy they need