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Biology > Key Concepts in Biology > Flashcards

Key Concepts in Biology Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is an electron microscope?

A

Invented in the 1930s, use electrons rather than light, higher magnification and resolution, can’t be used to view living cells

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2
Q

What is resolution?

A

How well a microscope distinguishes between two points that are close together.

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3
Q

Why can some cell structures be seen with an electron microscope but not with a light microscope?

A

Electron microscopes have a higher magnification and resolution

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4
Q

What is the formula for total magnification?

A

Total magnification = eyepiece lens magnification x objective lens magnification

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5
Q

What is the formula for sizes and magnifications?

A

Image size = magnification x real size

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6
Q

What do the SI prefixes milli-, micro-, nano-, and pico- mean?

A

x10^-3, x10^-6, x10^-9 and x10^-12 respectively

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7
Q

List and describe the parts of a plant cell and their functions.

A

Everything an animal cell contains plus:
A rigid cell wall, made of cellulose, which supports and strengthens the cell
A permanent vacuole, which contains cell sap (a weak solution of sugar and salts) and maintains internal pressure.
Chloroplasts- contain chlorophyll. The site of photosynthesis.

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8
Q

List and describe the parts of an animal cell and their functions.

A

Nucleus- contains genetic material (arranged into chromosomes) which controls the activities of the cell.
Cytoplasm- where most chemical reactions happen, contains enzymes which control them
Cell membrane- holds cell together and controls what goes in and out
Mitochondria- where most respiration reactions occur to provide energy
Ribosomes- involved in translation of genetic material in the synthesis of proteins.

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9
Q

What are the rules for drawing a field of view?

A

Draw what you see,draw image to the size it appears, add scale bar, label all cell structures with straight horizontal lines

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10
Q

How are sperm cells adapted to their function?

A

Long tail so it can “swim”, lots of mitochondria to provide energy needed to travel the distance, has an acrosome at the front of the “head” where it stores enzymes needed to digest its way through the cell membrane of the egg cell, contains a haploid nucleus.

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11
Q

How are egg cells adapted to their function?

A

Contains nutrients in the cytoplasm to feed the embryo, has a haploid nucleus, straight after fertilisation its membrane changes structure to stop any other sperm getting in so offspring has the correct amount of DNA

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12
Q

How are ciliated epithelial cells adapted to their function?

A

Some have cilia (hairlike structures) on the top surface of the cell which beat to move substances in one direction along the surface of the tissue.

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13
Q

What are the common parts of bacteria and their functions?

A

Chromosomal DNA (one long circular chromosome) which controls the cell’s activities and replication. Floats free in the cytoplasm.
Ribosomes- synthesise proteins
Cell membrane- controls what enters and leaves the cell
Plasmid DNA- small loops of extra DNA that aren’t part of the chromosome. Contain genes for drug resistance, etc… and can be passed between bacteria
Flagellum- long, hairlike structure which rotates so the bacterium can move

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14
Q

What is a eukaryotic cell?

A

Complex- include all animal and plant cells

Eukaryotes are organisms made up of eukaryotic cells

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15
Q

What is a prokaryotic cell?

A

Smaller and simpler, e.g. Bacteria

Prokaryotes are made up of a single prokaryotic cell

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16
Q

What are bacteria classed as?

A

Prokaryotes (a single prokaryotic cell)

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17
Q

What are enzymes?

A

Biological catalysts. Proteins. They have an active site where it joins onto its substrate (the molecule changed in the reaction) to catalyse the reaction.

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18
Q

Give examples and locations of enzymes

A

Carbohydrases e.g. amylase
Proteases
Lipases
All of these enzymes are in the digestive system
Glycogen synthase converts glucose into glycogen (found in the liver)

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19
Q

What are carbohydrates e.g. starch made up of?

A

Simple sugars(broken down by carbohydrases). Starch is made up of maltose and other sugars (broken down by amylase)

20
Q

What are proteins made up of?

A

Amino acids ( broken down by proteases)

21
Q

What are lipids made up of?

A

Glycerol and fatty acids (broken down by lipases)

22
Q

What do enzymes do?

A

Catalyse the synthesis and breakdown of substances such as carbohydrates, proteins and lipids by speeding up the rate of reaction

23
Q

Why is catalysis in enzymes important for life processes?

A

Reactions happen much faster without the need for high temperatures

24
Q

How do you test for starch in foods?

A

Iodine goes blueblack if starch is present

25
Q

How do you test for reducing sugars in food?

A

Use benedict’s reagent:
Add to a sample and heat in a water bath set to 75’C. A positive test will result in a coloured precipitate forming.
The colour change will go from blue to green, yellow, orange or brick red depending on the concentration of reducing sugars

26
Q

How do you test for proteins in food?

A

Use the biuret test:
Add a few drops of potassium hydroxide solution to make the solution alkaline then add some copper sulphate solution. The solution will turn purple if protein is present.

27
Q

How do you test for lipids in food?

A

Emulsion test:
Shake the substance with ethanol for approx 1 minute until it dissolves then pour into water. Lipids present will precipitate out of the liquid and show up as a milky emulsion. More lipid present will result in a more noticeable milky colour

28
Q

Describe how to use calorimetry to measure the energy content of foods.

A

Use a flammable food.
Weigh the food then skewer on a mounted needle.
Add a set mass of water (1cm cubed = 1g of water) to a boiling tube held with a clamp.
Measure the water temperature then set fire to the food.
Immediately hold the food under the boiling tube until it goes out, then relight it and repeat until it won’t catch fire any longer
Measure the temperature of the water, then calculate the energy content using the equation.

29
Q

What is the equation you need for calorimetry?

A

Energy of water (J) = mass of water (g) x temperature change in water (‘C) x 4.2
Energy per gram of food = energy in food/mass of food

30
Q

Why could calorimetry tests be inaccurate?

A

Some energy in the food is transferred to the environment. Minimise this by insulating the boiling tube e.g. with foil

31
Q

What is enzyme specificity?

A

Enzymes usually only work with one substrate

32
Q

What is an enzyme’s action due to?

A

Its active site

33
Q

What is the role of the active site in enzyme function?

A

It is where the enzyme joins on to the substrate to catalyse the reaction. Enzyme specificity is due to the active site since the substrate has to fit into the active site for the reaction to be catalysed (lock and key mechanism)

34
Q

Why do enzymes have a particular shape?

A

As a result of the sequence of amino acids in the chain

35
Q

How do enzymes become denatured?

A

A temperature or pH that is too high or low (for pH) will interfere with bonds holding the enzyme together which changes the shape of the active site so it can’t catalyse reactions

36
Q

How does temperature affect enzyme activity?

A

Increasing temperature increases enzyme activity up to the point at which the enzyme works best (the optimum temperature). After this the activity decreases, until the temperature gets too high and the enzyme denatures.

37
Q

How does substrate concentration affect enzyme activity?

A

Increasing substrate concentration increases enzyme activity because it increases the probability of the enzyme encountering a substrate molecule until all the active sites are full so adding more substrate has no effect.

38
Q

What is the effect of pH on enzyme activity?

A

A pH closer to the optimum will result in a higher enzyme activity but too high/low will result in the enzymes getting denatured

39
Q

What is the equation for the rate of reaction?

A 
Rate=1000/time 
Measured in s^-1
OR
Rate of reaction= change/time
Measured in cm cubed or g s^-1
40
Q

How are substances transported in and out of cells?

A

Diffusion, osmosis and active transport

41
Q

How are substances transported by active transport?

A

The movement of particles across a membrane against a concentration gradient using energy transferred by respiration

42
Q

How are substances transported by diffusion?

A

The net movement of particles from an area of high concentration to an area of low concentration. Particles actually move randomly but since there are more on one side, overall they move one way.

43
Q

How are substances transported by osmosis?

A

Like diffusion. Movement of water molecules from an area of high water concentration/low solute concentration to an area of low water concentration/high solute concentration

44
Q

What are the effects of osmosis in cells and tissues?

A

Dried out cells are flaccid, cells full of water are turgid. Animal cells which take in too much water may explode

45
Q

What is the equation for percentage change in mass?

A

Percentage change = (final mass - initial mass)/ initial mass x100

46
Q

what is an enzyme?

A

A biological catalyst

Biology (9 decks)

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