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Gcse Biology > Topic 1 - Key Concepts > Flashcards

Topic 1 - Key Concepts Flashcards

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1
Q

State two types of cell

A

Eukaryotic, 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 components of both plant and animak 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 celluar activities

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6
Q

Describe the structure of the cytoplasm

A

Fluid/jelly-like component 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 celluar reactions/chemical process

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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 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 vacoule
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 structural integrity

Prevents the cell bursting when water enters by osmosis

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14
Q

What does the permanent vacoule contain?

A

A solution of salts, sugars and organic acids (cells sap)

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15
Q

What is the function of the permanent vacoule?

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 chloroplast appear green?

A

Contain chlorophyll; a green pigment

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18
Q

List the organelles found in prokaryotic cell

A 
Chromosomal DNA
Plasmid DNA
Cell Wall
Cell membrane 
Ribosomes
Flagella
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19
Q

How is genetic information stored in prokaryotic cell?

A

Found free within the cytoplams:
Chromosomal DNA (single large loop of circular DNA)
Plasmid DNA

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20
Q

What are plasmids?

A

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

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21
Q

What is a flagellum?

A

Long, rotating, “whip-like” protrusion

Enables bacteria to move

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22
Q

What is a haploid cell?

A

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

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23
Q

What is a diploid cell?

A

A cell that contains two copies of each chromosome (full set of chromosomes)

46 chromosomes in humans

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24
Q

What are gametes?

A

Reproductive cells

They are haploid cells

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25
Q

Describe sexual reproduction in term of chromosome number?

A

Two haploid gametes fuse

Resulting embryo has two chromosomes for each gene and two copies for each allele

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26
Q

Describe how egg cells are adapted their function?

A

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

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27
Q

Describe how sperm cells are adapted to their function?

A

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

28
Q

Where are ciliated epithelial cells found?

A

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

29
Q

Describe the function of ciliated epithelial cells lining the airways

A

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

30
Q

What is magnification?

A

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

31
Q

How can the total magnification of an image be calculated from lens powers?

A

Total mag = eyepiece lens magnification x objective lens magnification

32
Q

How can the magnification of an image be calculated?

A

Magnification = size of image / size of specimen

33
Q

What is resolution?

A

The smallest distance between two obejcts that can be distinguished

34
Q

How does a lighy microscope work?

A

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

35
Q

What are advantages of light microscopes?

A

Inexpensive
Easy to use
Portable
Observe both dead and living specimens

36
Q

What is the disadvantage of light microscopes?

A

Limited resolution

37
Q

How does an electron microscope work?

A

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

38
Q

Name two types of electron microscopes

A

Transmission electron microscopes (TEM)

Scanning electron microscope (SEM)

39
Q

What is the advantage of electron microscopes?

A

Greater magnification and resolution

Which means some sub cellular structures e,g ribosomes can be seen

40
Q

Why do electron microscopes and have a greater magnification and resolution?

A

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

41
Q

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

A

Allow small sub-cellular structures to be observed in detail

Enable scientists to develop more accurate explanations about how cell structure relates to function

42
Q

What are the disadvantages of electron microscopes?

A

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

43
Q

Si Units

A

Mm: 10x-3
Um (micrometer):10x-6
Nm: 10x-9
Pm:10x-12

44
Q

What are enzymes?

A

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

45
Q

What is an advantage of enzymes in body?

A

They enable cellular reactions to take place at lower temperatures

46
Q

What is the active site of an enzymes?

A

The region of an enzyme to which a substrate molecule binds and the reaction takes place

47
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 enzyme’s active site.

48
Q

Describe the “lock and key” model

A

1) substrate collides with the active site of an enzyme
2) Substrate binds, enzyme-substrate complex forms
3) Substrate converted to products
4) Products released from the active site which is now free to bind to another substrate

49
Q

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

A

Temperature
pH
Substrate concentration

50
Q

Explaim how increasing temp intially affects the rate of enzyme-controlled reaction

A

As temperature increases molecules have more KE
Movement of molecules increase
Probability of a successful collision increases
More enzyme-substrate complexes form
Rate of reaction increases

51
Q

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

A

Temperature increases above the optimum
Increased vibrations break bonds in enzyme structure
Active site changes shape, enzyme is denatured
No more enzyme-substrate complexes can form
Rate of reaction decreases

52
Q

Explain how pH affects the rate of an enzyme-controlled reaction

A

Enzymes have an optimum pH
pH shifts from the optimum
Bonds in the enzyme’s structure are altered
Active site changes shape, enzyme is denatured
Rate of reaction decreases

53
Q

Explain how the substrate concentration affects the rate of an enzyme-controlled reaction

A

Substrate concentration increases
Number of substrate molecules in the same volumes increases
Probability of a successful collisions increases
More enzyme-substrate complexes form
Rate of reaction increased
Once all active sites, become full, the rate of reaction plateaus

54
Q

Draw a graph to show the effect of increasing substrate concentration on rate of an enzyme-catalysed reaction

A
55
Q

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

A

Rate = 1/time

Units S^-1

56
Q

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

A

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

57
Q

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

A

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

58
Q

What type of molecules are proteins and carbohydrates?

A

Polymers

59
Q

What are the monomers of carbohydrates?

A

Simple sugars

60
Q

Which group of enzymes catalyses the breakdown of carbohydrates?

A

Carbohydrases

61
Q

Which type of carbohydrase catalyses the breakdown of starch?

A

Amylase

62
Q

What are the monomers of proteins?

A

Amino acids

63
Q

What type of enzyme catalyses the breakdown of proteins?

A

Proteases

64
Q

What is the function of lipases?

A

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

65
Q

Why are small molecules synthesised into larger organic molecules in the body?

A

Large molecules are used for storage (glycogen) or are used to build structures (organelles)

66
Q

Which enzyme catalyses the formation of glycogen from glucose

A

Glycogen synthase

Gcse Biology (14 decks)

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