Unit 2 Cells: Basic Units Of Life - Cell Theory And Cell Wall

Question 1

What are 2 electron microscopes and what are they used for?

Answer 1

Transmission (TEM) - look at internal parts of specimens. ( 1000 000 x )
Scanning (SEM) - look at surface of specimens. (30 000 x )

Question 2

Photographs taken through microscopes are called…

Answer 2

Micrographs

Question 3

Name the old theories of The cell theory.

Answer 3

1) All living organisms are made of cells, so cells are the basic unit (building block) of all living organisms.

2) all living organisms consist of 1/more cells.

3) All cells originate from pre-existing cells by division, don’t just appear.

Question 4

Describe the modern cell theory.

Answer 4

4) Energy flow occurs inside cells and all chemistry of life happens inside cells.

5) All cells contain hereditary info (DNA) - passed from cell to cell during cell division.

6) Cells of living organisms have a similar chemistry ( chemical composition and metabolic activities).

Question 5

What are the differences between animal cells and plant cells and then the function of each?

Answer 5

Animal cells - Small/ absent vacuole
- Lysosome
- Centrosome ( centrioles )
- irregular shape
- no plastids

Plant cells - Large central vacuole
- chloroplast
- cell wall
- fixed shape
- many have plastids

Question 6

What are the 3 structures of the cell wall?

Answer 6

Primary cell wall - contains cellulose fibres ( carb ) and this helps flexibility of cell.
Middle lamella - contains pectin ( polysaccharide )
Secondary cell wall - contains lignin ( organic substance joins cellulose fibres to one another)

Question 7

Name the order of the structures of the cell wall on the outside of the cell membrane.

Answer 7

1) Secondary cell wall ( found in older cells )
2) Primary cell wall
3) Middle lamella

Question 8

Name the functions of the cell wall.

Answer 8

Permeability
Support structure - rigidity and maintains shape.