Cell structure

Question 1

What are the two types of cells?

Answer 1

Eukaryotic and prokaryotic

Question 2

What are the differences between
eukaryotic and prokaryotic cells?

Answer 2

Prokaryotic cells are much smaller than
eukaryotic cells.

Eukaryotic cells contain membrane
bound-organelles and a nucleus containing
genetic material, while prokaryotes do not.

Question 3

What is the prokaryotic cell wall
composed of?

Answer 3

Peptidoglycan

Question 4

How is genetic information stored in a
prokaryotic cell?

Answer 4

Found free within the cytoplasm as:
● Chromosomal DNA (single large loop of circular DNA)
● Plasmid DNA

Question 5

What are plasmids?

Answer 5

● Small, circular loops of DNA found free in the
cytoplasm and separate from the main DNA.
● Carry genes that provide genetic advantages
e.g. antibiotic resistance.

Question 6

What is order of magnitude?

Answer 6

A power to the base 10 used to quantify
and compare size.

Question 7

What is a centimetre (cm)?

Answer 7

1 x 10-2 metres

Question 8

What is a millimetre (mm)?

Answer 8

1 × 10-3 metres

Question 9

What is a micrometre (µm)?

Answer 9

1 × 10-6 metres

Question 10

What is a nanometre (nm)?

Answer 10

1 x 10-9 metres

Question 11

What is the difference in order of
magnitude between a human hair (100
µm) and the HIV virus (length = 100
nm)?

Answer 11

100 µm = 10-4 m
100 nm = 10-7 m
-4-(-7) = -4 + 7 = 3

Question 12

List the components of both plant and
animal cells (5)

Answer 12

● Nucleus
● Cytoplasm
● Cell membrane
● Mitochondria
● Ribosomes

Question 13

List the additional cell components found
in plant cells (3)

Answer 13

● Chloroplasts
● Permanent vacuole
● Cell wall

Question 14

Other than storing genetic information,
what is the function of the nucleus?

Answer 14

Controls cellular activities

Question 15

Describe the structure of the cytoplasm

Answer 15

● Fluid component of the cell.
● Contains organelles, enzymes and dissolved
ions and nutrients.

Question 16

What is the function of the cytoplasm?

Answer 16

Site of cellular reactions e.g. first stage
of respiration.

Transport medium.

Question 17

What is the function of the cell
membrane?

Answer 17

Controls the entry and exit of materials
into and out of the cell.

Question 18

What is the function of the mitochondria?

Answer 18

Site of later stages of aerobic respiration
in which ATP is produced.

Question 19

What is the function of the ribosomes?

Answer 19

Joins amino acids in a specific order
during translation for the synthesis of
proteins.

Question 20

What is the plant cell wall made of?

Answer 20

Cellulose

Question 21

What is the function of the plant cell
wall?

Answer 21

● Provides strength.
● Prevents the cell bursting when water
enters by osmosis.

Question 22

What does the permanent vacuole
contain?

Answer 22

Cell sap (a solution of salts, sugars and
organic acids)

Question 23

What is the function of the permanent
vacuole?

Answer 23

Supports the cell, maintaining its
turgidity

Question 24

What is the function of chloroplasts?

Answer 24

Site of photosynthesis

Question 25

Describe how sperm cells in animals are adapted to their function

Answer 25

● Haploid nucleus contains genetic information. ● Tail enables movement. ● Mitochondria provide energy for tail movement. ● Acrosome contains enzymes that digest the egg cell membrane.

Question 26

Describe how nerve cells in animals are adapted to their function

Answer 26

● Long axon allows electrical impulses to be transmitted all over the body from the central nervous system. ● Dendrites from the cell body connect to and receive impulses from other nerve cells, muscles and glands. ● Myelin sheath insulates the axon and speeds up the transmission of impulses along the nerve cell.

Question 27

Describe how muscle cells in animals are adapted to their function

Answer 27

● Arrangement of protein filaments allows them to slide over each other to produce muscle contraction. ● Mitochondria to provide energy for muscle contraction. ● Merged cells in skeletal muscle allow muscle fibre contraction in unison.

Question 28

Describe how root hair cells in plants are adapted to their function

Answer 28

● Large surface area to absorb nutrients and water from surrounding soil. ● Thin walls that do not restrict water absorption.

Question 29

Describe how xylem cells in plants are adapted to their function

Answer 29

●No upper or lower margins between cells to provide a continuous route for water to flow. ● Thick, woody side walls strengthen their structure and prevent collapse.

Question 30

Describe how phloem cells in plants are adapted to their function

Answer 30

● Sieve plates let dissolved amino acids and sugars be transported up and down the stem. ● Companion cells provide energy needed for active transport of substances along the phloem.

Question 31

What is cell differentiation?

Answer 31

The process by which cells become specialised

Question 32

What is cell differentiation?

Answer 32

The process by which cells become specialised

Question 33

Why is cell differentiation important?

Answer 33

Allows production of different tissues and organs that perform various vital functions in the human body

Question 34

At what point in their life cycle do most animal cells differentiate?

Answer 34

Early in their life cycle

Question 35

For how long do plant cells retain the ability to differentiate?

Answer 35

Throughout their entire life cycle

Question 36

What is the purpose of cell division in mature animals?

Answer 36

Repair and replacement of cells

Question 37

What changes does a cell go through as it differentiates?

Answer 37

Becomes specialised through acquisition of different sub-cellular structures to enable a specific function to be performed by the cell.

Question 38

Define magnification

Answer 38

The number of times bigger an image appears compared to the size of the real object.

Question 39

Define resolution

Answer 39

The smallest distance between two objects that can be distinguished.

Question 40

How does a light microscope work?

Answer 40

Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed.

Question 41

What are the advantages of light microscopes? (4)

Answer 41

● Inexpensive ● Easy to use ● Portable ● Observe both dead and living specimens

Question 42

What is the disadvantage of light microscopes?

Answer 42

Limited resolution

Question 43

How does an electron microscope work?