Download MCAS Biology Review 2: Smallest Unit of Life Big Picture Review

MCAS Biology Review 2: Smallest Unit of Life
Big Picture Review:
Cells:
 A cell is the smallest unit that is alive and can carry on all the processes of life
 All living things are made of cells
o Unicellular organisms are made of 1 cell
o Multicellular organisms are made of many cells
 Cells contain organelles, which are specialized compartments that carry out a specific
function
 Types of cells
o Eukaryotic cells contain a nucleus, such as animal and plant cells
o Prokaryotic cells do NOT contain a nucleus, such as bacteria
Cell Membrane:
 Made of molecules called phospholipids
 Phospholipid bilayer is the 2 layers of phospholipids that make up the cell membrane
 Cell membrane is fluid, which means it is constantly flowing and moving over the cells
 Cell membrane is selectively permeable, which means it allows small compounds, but not
large ones, to pass through
 Transportation – different ways materials move across the cell membrane
o Passive transport – requires no energy
 Diffusion: compounds move from high to low concentration
 Osmosis: diffusion of water
o Active transport – requires energy
 Endocytosis: large compounds are brought into the cell
 Exocytosis: large compounds are exported from the cell
o Types of Solutions:
 Hypotonic solution causes water to move into the cell; cell swells up
 Hypertonic solution causes water to move out of the cell; shell shrivels
 Isotonic solution causes no net movement of water into or out of cell
Cell Cycle
 The cell cycle is the phases of life in the cell
o M phase: Mitosis (cell division) occurs
o G1 phase: Cell grows
o S phase: DNA synthesis (chromosomes are copied)
o G2 phase: Cell grows
o M phase begins again
 Chromosomes must be copied before mitosis so new cells receive the same chromosomes
as old cells.
 Mitosis
o Division of cell into 2 new identical cells
o For growth, healing, repair
o Before mitosis, chromosomes copy themselves
 Sister chromatids: original chromosome and its exact copy are attached to
each other
o Phases of Mitosis:
MCAS Biology Review 2: Smallest Unit of Life




Prophase: Nuclear membrane falls apart and spindle fibers start to form
Metaphase: Sister chromatids line up along the middle of the spindle
fibers
Amaphase: Sister chromatids separate and move to opposite ends of the
cell
Telophase: Spindle fibers break down and the new nuclear membrane
forms around each set of chromosomes
 Cytokinesis occurs when cytoplasm actually divides, forming two
new cells
A good web site for cell-parts practice, and an animation of mitosis:
http://www.cellsalive.com/cells/cell_model.htm
(or Google “animal cell” and “Cell Models: An Interactive Animation” should come up)
Questions:
1. Scientists believe that the first organisms that appeared
on Earth were prokaryotic. Which of the following
best represents what the cell structure of these
organisms may have looked like?
MCAS Biology Review 2: Smallest Unit of Life
2. Which of the following statements correctly matches a
cell part with its function?
a.
b.
c.
d.
The cell membrane packages lipids for export
The mitochondria perform photosynthesis
The lysosome digests molecules
The nucleus produces energy
3. Which of the following is a main function of the cell
wall?
a.
b.
c.
d.
To store carbohydrates for later use
To give the cell a rigid structure
To package proteins for export
To carry out photosynthesis
4. Which of the following describes plant cells but not
animal cells?
a. The nucleus contains chromosomes
b. The ribosomes assist in protein synthesis
c. Plastids store starch made during
photosynthesis
d. Mitochondria produce energy through
respiration
5. If an animal cell is placed in distilled water, it will
swell and burst. The bursting is a result of which
biological process?
a.
b.
c.
d.
Active transport
Enzyme activity
Osmosis
Respiration
MCAS Biology Review 2: Smallest Unit of Life
6.
7.
MCAS Biology Review 2: Smallest Unit of Life
8. In the synthesis phase (S phase) of the cell body, a
body cell copies its DNA. This DNA replication
occurs in preparation for which of the following
processes?
a.
b.
c.
d.
Cellular respiration
Facilitated diffusion
Mitosis
Translation
Question 9 is an open-response question.
 BE SURE TO LABEL ALL PARTS OF THE QUESTION.
 Show all your work (diagrams, tables, or computations)
 If you do the work in your head, explain in writing how you did the work.
Write your answer to question 6 in the space provided in your Student Answer Booklet.
MCAS Biology Review 2: Smallest Unit of Life
The following are full-credit (4 point) answers for Question 9.
Example 1:
MCAS Biology Review 2: Smallest Unit of Life
MCAS Biology Review 2: Smallest Unit of Life
Example 2: