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Science > Cells And Microscopy > Flashcards

Cells And Microscopy Flashcards

1
Q

State the two types of cells.

A

-Eukaryotic (animals and plants
-Prokaryotic

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2
Q

What is the difference between a Eukaryotic and Prokaryotic cell?

A

Eukaryotic - contains a nucleus and membrane-bound organelles
Prokaryotic- doesn’t

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3
Q

List 5 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

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6
Q

Describe the structure of the cytoplasm.

A

Contains organelles, enzymes and dissolved ions and nutrients

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7
Q

What’s the function of cytoplasm?

A

Site of cellular reactions e.g first stage of respiration

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8
Q

What’s 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’s the function of mitochondria?

A

Later stages of aerobic respiration in which ATP is produced

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10
Q

What’s the function of ribosomes?

A

Joins amino acids in a specific order during translation

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11
Q

What 3 organelles are found in plant cells only?

A

-Large, permanent vacuole
-Cell wall
-Chloroplasts

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12
Q

What’s the cell wall made of?

A

Cellulose

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13
Q

What’s 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’s the function of the permanent vacuole?

A

Supports the cell, maintaining its turgidity

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16
Q

What’s the function of chloroplasts?

A

Site of photosynthesis

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17
Q

What are the 6 organelles found in Prokaryotic cells?

A

-Chromosomal DNA
-Plasmid DNA
-Cell wall
-Cell membrane
-Ribosomes
-Flagella

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18
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

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19
Q

What’s flagellum?

A

Enables bacteria to move

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20
Q

What is a haploid cell?

A

Cell that contains a single copy of each chromosome (half the number of chromosomes)
E.g 23 chromosomes in humans

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21
Q

What’s a diploid cell?

A

Cell that contains two copies of each chromosome
E.g 46 chromosomes in humans

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22
Q

What are gamates?

A

-Reproductive cells (egg and sperm cells)
-They are haploid cells

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23
Q

How are egg cells adapted to their function?

A

-haploid nucleus contains genetic material
-mitochondria in cytoplasm produce energy for the developing embryo
-cytoplasm contains nutrients
-cell membrane hardens after fertilisation

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24
Q

How are sperm cells adapted to their function?

A

-haploid nucleus contains genetic information
-tail enables movement
-mitochondria provides energy for tail movement
-acrosomes contains enzymes that digest the egg cell membrane

25
Q

How can the magnification of an image be calculated?

A

Magnification = size of image/ size of specimen

26
Q

How do light microscopes work?

A

Passes a beam of light through which travels through the eyepiece lens

27
Q

What are 4 advantages of light microscopes?

A

-inexpensive
-easy to use
-portable
-observe both living and dead specimens

28
Q

What is a disadvantages of light microscopes?

A

Limited resolution

29
Q

How does an electron microscope work?

A

Uses a beam of electrons which are focused using magnets, electrons hit a fluorescent screen which emits visible light, producing an image

30
Q

What’s an advantage of an electron microscope?

A

Greater magnification and resolution

31
Q

What are 4 disadvantages of an electron microscope?

A

-expensive
-large so less portable
-require training to use
-only dead specimens can be observed

32
Q

What are enzymes?

A

Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves

33
Q

What’s an advantage of enzymes in the body?

A

They enable cellular reactions to take place at lower temperatures

34
Q

What is the active site of an enzyme?

A

Substrate molecule binds and the reaction takes place

35
Q

Why are enzymes described as having a ‘high specificity’ for their substrate?

A

Only substrates with a specific, complementary shape can fit into an enzymes active site

36
Q

Describe the ‘lock and key’ model?

A

-substrate collides with the active site of an enzyme
-substrate binds, enzyme-substrate complex forms
-substrate converted to products
-products released from the active site which is now free to bind to another substrate

37
Q

What factors affect the rate of an enzyme-controlled reaction?

A

-temperature
-pH
-substrate concentration

38
Q

Explain how increasing temperature initially affects the rate of an enzyme-controlled reaction.

A

-as temp increases molecules have more KE
-movement of molecules increases
-probablility of a successful collision increases
-more enzyme-substrate complexes form
-rate of reaction increases

39
Q

Explain how increasing temperature above the optimum affects the rate of an enzyme-controlled reaction.

A

-temp increases above optimum
-increased vibrations break bonds in enzymes structure
-active site changes shape, enzyme is denatured
-no enzyme-substrate complexes can form
-rate of reaction decreases

40
Q

How can the rate of an enzyme-controlled reaction be calculated when given a value for time?

A

Rate= 1/ time

41
Q

What are the units for rate?

A

S^-1

42
Q

Why must large organic molecules be broken down into smaller, simple molecules in the body?

A

-large molecules are too big to be absorbed across the surface of the gut wall
-large molecules are broken down into smaller molecules for absorption into the bloodstream

43
Q

Give an example of the breakdown of large molecules into smaller molecules in plants.

A

Starch is broken down by enzymes into simple sugars which are respired to release energy

44
Q

What type of molecules are proteins are carbohydrates?

A

Polymers

45
Q

What are the monomers of carbohydrates?

A

Simple sugars

46
Q

Which group of enzymes catalyses the breakdown of carbohydrates?

A

Carbohydrases

47
Q

Which type of carbohydrase catalyses the breakdown of starch?

A

Amylase

48
Q

What are the monomers of proteins?

A

Amino acids

49
Q

Which type of enzyme catalyses the breakdown of proteinss.

A

Proteases

50
Q

What is the function of lipases?

A

Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol

51
Q

Which enzyme catalyses the formation of glycogen from glucose?

A

Glycogen synthase

52
Q

What is simple diffusion?

A

The net movement of molecules from an area of high concentration to an area of low concentration

53
Q

What molecules enter and leave cells via simple diffusion through the cell membrane?

A

Small molecules e.g oxygen, water, glucose, amino acids

54
Q

What 3 factors affect the rate of diffusion?

A

-temperature
-concentration gradient
-surface area of cell membrane

55
Q

Define osmosis.

A

The net movement of water molecules from an area of high water concentration to an area of low water concentration through a partially permeable membrane

56
Q

What is active transport?

A

The movement of molecules across a cell membrane from an area of low concentration to an area of high concentration

57
Q

How is percentage change in mass calculated?

A

% change = final mass-initial mass/ initial mass x 100

58
Q

What’s the role of the nucleus?

A

Controls cells activities

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