Topic 1 - Cells and Microscopy Flashcards

1
Q

State the two types of cell

A

Eukaryotic (animals and plants) and

prokaryotic

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2
Q

What is the difference between a

eukaryotic and prokaryotic cell?

A

A eukaryotic cell contains a nucleus and
membrane-bound organelles. A
prokaryotic cell does not.

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3
Q

List the components of both plant and

animal cells

A
● Nucleus
● Cytoplasm
● Cell membrane
● Mitochondria
● Ribosomes
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4
Q

How is genetic information stored in a

eukaryotic cell?

A

Within the nucleus, arranged in

chromosomes

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5
Q

Other than storing genetic information,

what is the function of the nucleus?

A

Controls cellular activities like protein synthesis and cell division

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6
Q

Describe the structure of the cytoplasm

A

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

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7
Q

What is the function of the cytoplasm?

A

Site of cellular reactions e.g. first stage

of respiration

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8
Q

What is the function of the cell membrane?

A

Controls the entry and exit of materials

into and out of the cell

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9
Q

What is the function of the mitochondria?

A

Site of later stages of aerobic respiration

in which ATP is produced

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10
Q

What is the function of the ribosomes?

A

Joins amino acids in a specific order

during translation

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11
Q

Which organelles are found in plant cells

only?

A

● Large, permanent vacuole
● Cell wall
● Chloroplasts

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12
Q

What is the cell wall made of?

A

Cellulose

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13
Q

What is the function of the cell wall?

A

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

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14
Q

What does the permanent vacuole contain?

A

A solution of salts, sugars and organic

acids

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15
Q

What is the function of the permanent

vacuole?

A

Supports the cell, maintaining its turgidity

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16
Q

What is the function of the chloroplasts?

A

Site of photosynthesis

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17
Q

When looking at a cell using a light
microscope, why do chloroplasts appear
green?

A

Contain chlorophyll, a green pigment

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18
Q

List the organelles found in prokaryotic

cells

A
● Chromosomal DNA
● Plasmid DNA
● Cell wall
● Cell membrane
● Ribosomes
● Flagella
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19
Q

How is genetic information stored in a

prokaryotic cell?

A

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

20
Q

What are plasmids?

A

● 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

21
Q

What is the prokaryotic cell wall

composed of?

A

Peptidoglycan

22
Q

What is a flagellum?

A

● Long, rotating, ‘whip-like’ protrusion

● Enables bacteria to move

23
Q

What is a haploid cell?

A

A cell that contains a single copy of each
chromosome (half the number of chromosomes)
e.g. 23 chromosomes in humans

24
Q

What is a diploid cell?

A

A cell that contains two copies of each
chromosome (full set of chromosomes)
e.g. 46 chromosomes in humans

25
Q

What are gametes?

A

● Reproductive cells (e.g. egg and sperm cells)

● They are haploid cells

26
Q

Describe sexual reproduction in terms of

chromosome number

A

● Two haploid gametes fuse
● Resulting embryo has two chromosomes for each
gene and two copies of each allele ∴ diploid

27
Q

Describe how egg cells are adapted to their function

A

● Haploid nucleus contains genetic material
● Mitochondria in cytoplasm produce energy for the developing
embryo
● Cytoplasm contains nutrients for the developing embryo
● Cell membrane hardens after fertilisation, preventing the entry
of other sperm and ensuring the zygote is diploid

28
Q

Describe how sperm cells are adapted to their

function

A

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

29
Q

Where are ciliated epithelial cells found?

A

Found lining the surface of structures such as the respiratory tract and uterus.

30
Q

Describe the function of ciliated epithelial

cells lining the airways

A

Move in synchronised waves to beat mucus (containing dirt and pathogens) up
to the back of the throat where it can be
swallowed.

31
Q

What is magnification?

A

The number of times bigger an image
appears compared to the size of the
specimen

32
Q

How can the total magnification of an

image be calculated from lens powers?

A

total magnification = eyepiece lens magnification x objective lens magnification

33
Q

How can the magnification of an image be

calculated?

A

size of image / size of specimen

34
Q

What is resolution?

A

The smallest distance between two

objects that can be distinguished

35
Q

How does a light microscope work?

A

Passes a beam of light through a specimen

which travels through the eyepiece lens, allowing the specimen to be observed.

36
Q

What are the advantages of light microscopes?

A

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

37
Q

What is the disadvantage of light microscopes?

A

Limited resolution

38
Q

How does an electron microscope work?

A

It uses a beam of electrons which are
focused using magnets. The electrons hit
a fluorescent screen which emits visible
light, producing an image.

39
Q

Name the two types of electron microscope

A

Transmission electron microscope (TEM)

Scanning electron microscope (SEM)

40
Q

What is the advantage of electron microscopes?

A

Greater magnification and resolution

41
Q

Why do electron microscopes have a greater magnification and resolution?

A

They use a beam of electrons which has a shorter wavelength than photons of light

42
Q

How have electron microscopes enabled scientists to develop their understanding of cells?

A

● Allow small sub-cellular structures (e.g.mitochondria, ribosomes) to be observed in detail
● Enable scientists to develop more accurate
explanations about how cell structure relates to function

43
Q

What are the disadvantages of electron

microscopes?

A

● Expensive
● Large so less portable
● Require training to use
● Only dead specimens can be observed

44
Q

How do you convert from m to mm?

A

× 1000 (× 10^3)

45
Q

How do you convert from m to µm?

A

× 1 000 000 (× 10^6)

46
Q

How do you convert from m to nm?

A

× 1 000 000 000 (× 10^9)

47
Q

How do you convert from m to pm?

A

× 1 000 000 000 000 (× 10^12)