Some examples of diffusion on living organisms

Difusion in Living Organisms
-Gaseous exchange during respiration and photosynthesis
-Excretion of waste products
-Absorption of digested food

What are the factors that determine the rate of diffusion?

The factors are

-Temperature

-Size of particles

-Whether the solution has ben mixed
-Thickness of barrier
-Concentration gradient
-Surface area

Do molecules even stop moving?

Diffusion stops when equal concentrations of a substance in two regions is reached

When will diffusion stop?

Diffusion will stop when the concentration of molecules is the same everywhere-evenly spread (Equilibrium)

What is diffusion?

Diffusion describes the spread of molecules through random motion from places of higher concentration to places of lower concentration.

Table of procedures

Biology: Processes of life-How big can a cell get? (29/3/2012)

Table of procedures:

Steps	Procedures
1	Fold the paper towel into 2
2	Cut into 3 strips of about 30x20mm
3	Briefly soak the strips into cabbage juice
4	Remove immediately once the paper turns light purple
5	Spread them open and leave aside to dry on the white tile
6	Cut the agar block to the following specifications: a. 3 pieces of 5x5x5mm b. 1 piece of 5x5x20mm c. 1 piece of 10x10x10mm
7	Label your petri dish accordingly based on the solutions that are assigned to you in step 2
8	Immerse one piece of agar of size 5x5x5mm, 5x5x20mm and 10x10x10mm into the lemon juice solution
9	Record the time it takes to change colour completely
10	Immerse the other two pieces of 5x5x5mm agar into the 2 remaining liquids.
11	Observe the colour change and record in Table 2
12	Introduce a few drops of each of the 3 solutions onto a different strip of the cabbage juice soaked 2-ply paper towel
13	Observe the colour change and record the results in Table 2
14	Transfer 2 square centimeter of each solution into separate test tubes.
15	Label the test tubes accordingly
16	Add an equal amount of cabbage juice into ach test tube
17	Record the colour change in Table 2

Function of organelles

Function of:
Nucleus-->Controls all activities happening in the cell
              --> Contains genetic materials
Nuclear membrane-->Separates the nucleus from the cytoplasm
                              -->controls what enters and leaves the nucleus
Cytoplasm-->allows substances to move freely in the cell
Cell membrane-->controls the substances moving in and out of the cell
Vacuole-->export unwanted substances out of the cell
             -->Isolating materials that might be harmful to the cell
Mitochondria-->provides energy for the cell
Chloroplasts-->Contain chlorophyll for the plant to photosynthesize

Diagram of animal cell

Diagram of plant cell

Difference between plant and animal cell

Plant cell	Animal cell
Has chloroplasts	Has no chloroplasts
Has a cell wall	Does not have a cell wall
One large central vacuole	One or more small vacuoles
Centrioles present in all animal cell	Centrioles only present in lower plant forms

Similarities between plant and animal cell

Both have
-nucleus
-mitochondria
-chloroplasts
-ribosomes
-golgi apparatus
-cell membrane
-endoplasmic reticulum(ER)

Difference between prokaryotic and eukaryotic cells

Prokaryotic cells	Eukaryotic cells
Does not have a nucleus	Has a nucleus
Lack some organelles	Does no lack organelles
Not found in humans	Found in humans
Unicellular	Often multicellular
Reproduce/divide by binary fission	Reproduce/divide by mitosis