Download 2.4 Worksheet Solutions

2.3 – The Need for Cell Division
1. Two cells, a and b, have different sizes.
a
a. Find the volume of each cell.
Va=8u3
b. Find the surface area of each cell.
SAa=24u2
b
Vb=27u3
SAb=54u2
c. Which cell has more surface area per unit of volume?
 cell a has a more surface area per unit volume
cell A: 24÷8 = 3
cell B: 54÷8 = 2
2. When a cell has grown too big, what are two difficulties that arise
from its large size?
 Not enough surface area to absorb nutrients/expel waste
 It takes too long for messages to travel through cell
3. Two cells, a and b, are growing in slightly different shapes.
a. Find the volume of each cell.
Va=10u3
Vb=10u3
b. Find the surface area of each cell.
SAa=42u2
SAb=34u2
c. Which cell needs to divide more urgently to considering
surface area and volume?
 Cell b needs to divide because it has less surface area for
the same volume
4. Here are 2 cells:
Cell A
Cell B
a. Which cell has SMALLER surface area?
cell A
b. Which cell has GREATER surface area?
cell B
c. Which cell would be more useful in the small intestine, where
nutrients are absorbed from food after it leaves the stomach?
Explain your answer.
 The one with greater surface area (cell B) would be better
able to absorb nutrients from the intestine because there is
more surface for the nutrients to pass through.
5. Which cell would you expect to be bigger: a cell from the earlobe or
a cell from the heart? Explain.
 A cell that works harder burns more energy and has to
absorb more food and release more waste
 This need a cell with lots of surface area a small cell
 The heart works harder than the earlobe so the heart’s cell
would be smaller
2.4 – Cell Specialization
1. In plants, the cell wall comes in different thicknesses. How could
you tell by feeling the plant tissue (ex leaf, stalk, root, etc) how
thick the cell walls are?
 Thick cell walls make for tougher plant tissue
2. Do humans prefer to eat plant tissue with thick or thin cell walls?
 Humans prefer eating soft food, so they like thin cell walls
3. Why do cells die if the cell wall is too thick?
 It is harder for water and nutrients to diffuse through a thick wall
4. What is pectin and what does it do?
 Pectin is a like a glue that makes cells stick to their neighbours
5. What would happen to a carrot that was dipped in a solution that
dissolved pectin?
 The cells would fall away from each other and the carrot would
become mushy or fall apart completely
Complete the chart of specialized animal cells below
Cell type
Purpose
Special shape or features
Nerve
-Conduct electric
signals
-Have long arms with fatty coating
Lung
-Exchange gases
-Thin, allowing air to pass through
Red blood
-Carry oxygen to
body
-Small, contain hemoglobin
protein that carries oxygen
White blood -Attack invaders
Stomach
-Digests food
-Protect body from
stomach acid
-Moves like an amoeba, engulfing
and destroying invaders
-Contains many golgi apparatuses
to release digestive proteins
-Covered in mucus
Fat
-Store nutrients
Have large vacuoles for storage
Small
intestine
-Absorb nutrients
from food
-Has villi (small projections) to
increase surface area for
absorption
Pop Quiz!!!
1. If a cell needs to make a protein, what part of the cell gives the
command to make it?
Nucleus
2. What is the organelle that produces proteins?
Ribosomes
3. What’s the network of folded membranes used to transport proteins
called?
Endoplasmic Reticulum
4. When a protein must be sent out of the cell, where does it get
packaged (into a vesicle)?
5. What is the fluid inside the cell?
Golgi Body
Cytoplasm
6. To leave the cell, the protein vesicle must pass through the
Cellular Membrane