Topic 1: Cell Biology

Question 1

What are the 3 points of the cell theory?

Answer 1

1. All living organisms are composed of 1 or more cells
2. The cell is the basic unit of life, structure and organization in organism
3. All cells come from pre-existing cells

Question 2

What are the 3 exceptions to the cell theory?

Answer 2

1. Fungi: consists of narrow, thread-like structures called hyphae, which have both a cell membrane and a cell wall. Many are divided by cross wall like structures called septa and are long tubes w/many nuclei spread along it.
2. Algae: unicellular and some types can grow to be very large
3. Striated Muscle: much larger than normal animal cells and have an average length of 30 mm in humans. Are multi-nucleated.

Question 3

What are the functions of uni-cellular organisms (living things)?

Answer 3

M - metabolism: chemical reactions inside the cell
R - reproduction: produce offspring sexually/asexually
S - sensitivity/response: responsiveness to external stimuli
H - homeostasis: maintain a stable Internal environment
E - excretion: exhibit the removal of waste products
N - nutrition: exchange materials/gasses w/environment for growth
G - growth: increase in shape and size

Question 4

Example of a unicellular organism:

Answer 4

Paramecium (heterotroph):

• responsiveness: surrounded by small hairs called cilia which allow it to move
• nutrition: engulf food via a specialized membranous feeding grove called a cytosome

-metabolism: food particles are enclosed within small vacuoles that contain enzymes for digestion

• excretion: solid wastes are removed via an anal pore, liquid wastes are pumped out via contractile vacuoles
• homeostasis: essential gasses enter (O2) and exit (CO2) the cell via diffusion
• reproduction: paramecia divide asexually (fission)

Question 5

How is a larger surface area to volume ratio achieved in cells?

Answer 5

is achieved when the cell gets smaller, making diffusion of nutrients and waste materials more effective
- there is a physical limit to size a cell can grow
- multicellular organisms are the result of working around this limit

Question 6

Rate of Metabolism

Answer 6

mass/volume

Question 7

Rate of material exchange:

Answer 7

surface area

Question 8

How to increase SA:Volume ratio

Answer 8

• villi increase SA of inner lining of intestinal tissue
• microvilli in alveoli increase total membrane surface