1.1 Into to cells

Question 1

Unicellular organisms

Answer 1

1 cell

Have 7 functions

Question 2

Multicellular organisms

Answer 2

Many cells that have individual rolls

Question 3

Emergent propertis

Answer 3

‘The sum of the total’

Properties that come together to combine to form something

Question 4

Exemptions to the cell theory

Answer 4

striated muscle - long, multiple nuclei

Giant algae - 1 nucleus, but grows too big for theory

Aseptate hyphae - many shared nuclei

Question 5

Features of all cells

Answer 5

MR. H GREN
- Metabolism
- Reproduce
- Homeostasis
- Growth
- Excretion
- Nutrition

Question 6

Calculation of magnification

Answer 6

Magnification = Image size (with ruler) ÷ Actual size (according to scale bar)

Question 7

7 functions of a unicellular organism

Answer 7

Metabolism – Living things undertake essential chemical reactions
Reproduction – Living things produce offspring, either sexually or asexually
Sensitivity – Living things are responsive to internal and external stimuli
Homeostasis – Living things maintain a stable internal environment
Excretion – Living things exhibit the removal of waste products
Nutrition – Living things exchange materials and gases with the environment
Growth – Living things can move and change shape or size

MR SHENG

Question 8

functions of life in Paramecium and one named photosynthetic unicellular organism

Answer 8

Paramecium:
- are surrounded by small hairs called cilia which allow it to move (responsiveness)
- engulf food via a specialised membranous feeding groove called a cytostome (nutrition)
- Food particles are enclosed within small vacuoles that contain enzymes for digestion (metabolism)
- Solid wastes are removed via an anal pore, while liquid wastes are pumped out via contractile vacoules (excretion)
- Essential gases enter (e.g. O2) and exit (e.g. CO2) the cell via diffusion (homeostasis)
- Paramecia divide asexually although horizontal gene transfer can occur via conjugation (reproduction)

Scenedesmus (autotroph)
- nutrition / excretion
- metabolism
- reproduction
- responsiveness

Question 9

Calculation of actual size

Answer 9

Must calc. magnification first
Actual Size = Image size (with ruler) ÷ Magnification

Question 10

Stem Cells

Answer 10

Stem cells are unspecialised cells that have two key qualities:
- Self Renewal = They can continuously divide and replicate

• Potency = They have the capacity to differentiate into specialised cell types

Stem cells are necessary for embryonic development as they are an undifferentiated cell source from which all other cell types may be derived

Stem cells have become a viable therapeutic option for when tissues become damaged

Question 11

Use of stem cells to treat Stargardt’s disease

Answer 11

• Stargardt’s disease is an inherited form of juvenile macular degeneration that causes progressive vision loss to the point of blindness
• Caused by a gene mutation that impairs energy transport in retinal photoreceptor cells, causing them to degenerate
• Treated by replacing dead cells in the retina with functioning ones derived from stem cells

Also used in Parkinson’s Disease:
- degenerative disorder of the central nervous system caused by the death of dopamine-secreting cells in the midbrain
- Treated by replacing dead nerve cells with living, dopamine-producing ones