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Science > Key Concepts in Biology > Flashcards

Key Concepts in Biology Flashcards

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Biology 101 flashcards
1
Q

What is the formula for magnification?

A

Magnification = Eyepiece lens X Objective lens
OR
Magnification = Image Size/Actual Size

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2
Q

Define resolution

A

The smallest distance between 2 points that can still be seen as 2 points

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3
Q

How does an electron microscope work?

A

Beams of electrons pass through a specimen to build up an image

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4
Q

What is the name of a cell with a nucleus?

A

Eukaryotic

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5
Q

Name the 5 main subcellular structures in eukaryotic cells

A

Nucleus, cell membrane, cytoplasm, mitochondria and ribosome

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6
Q

What is the name of the circular area you see in a light microscope?

A

The field of view

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7
Q

What is the cell wall made out of and what does it do?

A

Cellulose, supports/protects the cell

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8
Q

What does the chloroplasts contain and what does it do?

A

Chlorophyll, which traps energy transferred from the Sun which is used for photosynthesis

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9
Q

What does the vacuole do?

A

Stores cell sap and helps to keep the cell firm/rigid

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10
Q

What do the cells that the small intestine do and how have they adapted?

A

They absorb small food molecules produced by digestion, they are adapted by having membranes with many tiny folds called microvilli. These adaptations increase the surface area of the cell, as the more area for molecules to be absorbed, the faster absorption happens

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11
Q

What happens during sexual reproduction?

A

2 specialised cells (gametes - in humans, the egg and sperm cell) fuse to create a cell that develops into an embryo.

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12
Q

Define diploid and hapolid

A

Diploid - cells with 2 sets of chromosomes

Haploid - cells with 1 copy of each chromosome

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13
Q

Where is the nutrients stored to supply the fertilised egg cell with energy and raw materials for the growth and development of the embryo?

A

The cytoplasm

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14
Q

What does the jelly coat do?

A

It protects the egg cell and hardens after fertilisation to ensure that only 1 sperm cell enters the egg cell

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15
Q

What is the acrosome?

A

It is a small vacuole at the tip of the head of a sperm cell that contains enzymes that break down the substances in the egg cell’s jelly coat which allows the sperm cell to burrow inside

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16
Q

What do the mitochondria in the sperm cell do?

A

It releases lots of energy to power the tail

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17
Q

Where does fertilisation occur?

A

In the oviducts of the female reproductive system

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18
Q

How are oviduct cells adapted for transporting egg cells towards the uterus?

A

Cilia - cells that line the oviduct

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19
Q

What is special about prokaryotic cells, and what do they have instead?

A

They don’t have mitochondria, chloroplasts, nuclei or chromosomes. Instead their cytoplasm contains one large loop of chromosomal DNA, which controls most of the cell’s activities

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20
Q

What are the smaller loops of DNA in prokaryotic cells called and what do they do?

A

Plasmids - control a few of the cell’s activities

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21
Q

How does bacteria get energy for growth and development?

A

By releasing digestive enzymes into their environments and then absorb digested food into their cells

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22
Q

What is synthesis?

A

Building larger molecules from smaller subunits

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23
Q

Why are complex carbohydrates and proteins both polymers?

A

Because they are made up of many similar small molecules (monomers) joined in a chain

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24
Q

Why does synthesis happen very slowly?

A

Because the subunits rarely collide with enough force or in the right orientation to form a bond

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25
Q

What are the catalysts that speed up breakdown (like digestion) and synthesis reactions?

A

Enzymes - biological catalysts that increase the rate of reactions

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26
Q

What is the name of the substances that enzymes work on and the substances that are produced?

A

Substrates and products

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27
Q

Where is amylase found and what reaction does it catalyse?

A

In saliva and small intestine; breaking down starch to small sugars, such as maltose

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28
Q

Where is catalase found and what reaction does it catalyse?

A

In most cells, but especially liver cells; breaking down hydrogen peroxide made in many cell reactions to water and oxygen

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29
Q

Where is starch synthase found and what reaction does it catalyse?

A

In plants; synthesis of starch from glucose

30
Q

Where is DNA polymerase found and what reaction does it catalyse?

A

In the nucleus; synthesis of DNA from its monomers

31
Q

What do chemical reagents do?

A

Identify changes in food

32
Q

What happens when an equal volume of Benedict’s solution is mixed with a food solution and placed in a hot water bath for a few mins?

A

Reducing sugars in the food cause a reduction reaction, which changes the colour of the solution and may form a precipitate

33
Q

What does a blue-black colour indicate when iodine solution is added to a food?

A

It is in contact with starch

34
Q

What happens in the biuret test?

A

Potassium hydroxide is mixed with a food solution. 2 drops of copper sulfate solution are then added and if the pale blue solution turns purple, it is indicated that there is protein in the food

35
Q

What happens in the ethanol emulsion test and what does it test for?

A

It tests for fats and oils (lipids); the food is mixed with ethanol and shaken. Some of that mixture is then poured into water and shaken again. Fats and oils dissolved in the ethanol float to the surface, forming a cloudy emulsion, when the mixture is left to stand

36
Q

What does a calorimeter measure?

A

The amount of energy in a food

37
Q

What is the active site in the 3D shape of enzymes?

A

It is where the substrate of the enzyme fits at the start of the reaction

38
Q

Different enzymes have active sites of different shapes. What does this explain?

A

It explains why every enzyme can only work with specific substrates that fit the active site

39
Q

Name a model that shows how enzymes work because of how the enzyme and substrate fit together

A

The lock-and-key model

40
Q

How does an enzyme create its product?

A

Two different substrate molecules are held tightly in the active site in the right position for bonds to form between them and make a product molecule. The product molecule is a slightly different shape to the substrate molecules so it no longer fits tightly in the active site and is released.

41
Q

What does it mean if an enzyme is denatured?

A

When changes in an enzyme’s environment (like pH or temp.) affect how the protein folds up , so it changes the shape of its active site. If it changes too much, the substrate will no longer fit neatly in it and the enzyme will no longer catalyse the reaction

42
Q

How do you calculate the rate of reaction?

A

Rate of reaction (g/min) = Amount in g (e.g. 100g of starch)/time taken to be digested (mins)

43
Q

What is an enzyme’s optimum temperature?

A

The temperature at which the enzyme works fastest

44
Q

Define diffusion

A

A physical process that refers to the net movement of molecules from a region of high concentration to one of lower concentration

45
Q

What does a difference between 2 concentrations form?

A

A concentration gradient

46
Q

Do particles diffuse up or down a concentration gradient?

A

Down

47
Q

What does it mean if the concentration gradient is steeper?

A

The faster diffusion occurs and the bigger the difference between the concentrations

48
Q

What does diffusion allow?

A

Small molecules (like oxygen and carbon dioxide) to move into and out of cells

49
Q

What is partially permeable/semi-permiable?

A

A membrane that allows some molecules through it and not others

50
Q

What molecules can get through a cell membrane?

A

They trap soluble molecules inside cells, but water molecules can diffuse through the membrane

51
Q

What is osmosis?

A

The diffusion of small molecules of a solvent through a semi-permeable membrane

52
Q

When will the overall movement of solvent molecules stop?

A

When the concentration of solutes is the same on both sides of a membrane

53
Q

How do you calculate percentage change in mass?

A

(Final mass-initial mass)/Initial mass X 100

54
Q

What does active transport do?

A

It helps cells that may need to transport molecules against a concentration gradient or transport molecules that are too big to diffuse through the cell membrane

55
Q

How does active transport work?

A

This process is carried out by transport proteins in cell membranes. The transport proteins capture certain molecules and carry them across the cell membrane. This is an active process and so requires energy.

56
Q

What type of process are osmosis and diffusion, and what does this mean?

A

They are passive processes, and so do not require an input of energy

57
Q

What is microvilli?

A

Membranes with tiny folds that increase the surface area of a cell. The more area for molecules to be absorbed, the faster absorption happens

58
Q

What molecules make up proteins?

A

Amino acids

59
Q

What molecules make up carbs?

A

Glucose molecules

60
Q

What molecules make up lipids?

A

Lipid Fatty acids

61
Q

How do you calculate the rate of reaction?

A

1/Time

62
Q

What is a buffer solution?

A

A solution with a particular pH value

63
Q

What is osmosis?

A

The diffusion of water molecules from a high concentration of water to a low concentration of water molecules across a partially permeable membrane

64
Q

When does osmosis stop?

A

When there is no concentration gradient; when the concentration of solutes is the same on both sides of the membrane (once equilibrium is reached)

65
Q

What is a passive process and give an example?

A

Where no energy is needed - diffusion

66
Q

What is an ion?

A

A charged molecule

67
Q

What is active transport?

A

When molecules move against the concentration gradient from low to high

68
Q

Give an example as to why diffusion is important in the body

A

To move oxygen into cells and remove carbon dioxide

69
Q

Where does active transport get its energy from?

A

Respiration

70
Q

What does active transport make it possible for cells to do?

A

To absorb ions from very dilute solutions

71
Q

How can you investigate osmosis?

A

Osmosis in potatoes

% change in mass of potato pieces = Final mass-Initial Mass/Initial Mass X 100

72
Q

What is calorimetry?

A

Finds the amount of energy in a sample of food

Science (23 decks)

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