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Ayyan's Handy Materials > Biology for IGCSE (Chapters 2-6) > Flashcards

Biology for IGCSE (Chapters 2-6) Flashcards

1
Q

Define cells

A

The smallest units from which all organisms are made

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2
Q

Too see smaller things inside a cell, a/n _____________ microscope is used. A picture taken with it is called a/n ____________________

A

Electron, electron micrograph

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3
Q

What part of a cell is located around the outside?

A

Cell membrane

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4
Q

What is meant by, “A cell membrane is said to be partially permeable”?

A

It means that a cell membrane will let some substances through but not others

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5
Q

What are cell walls in plants made up of?

A

Cellulose

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6
Q

What is cytoplasm?

A

The jelly-like material that fills a cell

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7
Q

What is a vacuole?

A

A fluid-filled space inside a cell which is surrounded by its own membrane

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8
Q

What is the name of the solution of sugars and other substances that fills a vacuole?

A

Cell sap

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9
Q

What is the name for the small vacuoles in animal cells, which also contain solutions?

A

Vesicles

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10
Q

What is the importance of the nucleus in a cell?

A

It is where the genetic information is stored.

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11
Q

What is genetic information kept on in a nucleus?

A

Chromosomes, which are inherited from the organism’s parents.

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12
Q

What are chromosomes made of?

A

DNA (deoxyribonucleic acid)

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13
Q

If chloroplasts are never found in animal cells, where are they found?

A

Within the cells of all auto-trophic organisms

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14
Q

What is the mitochondrion?

A

A small structure in a cell, where aerobic respiration releases energy from glucose; it is the powerhouse of the cell

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15
Q

Can mitochondria be seen via a light microscope?

A

No, they are so small that they can only be seen with an electron microscope.

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16
Q

What are ribosomes?

A

Very small structures in a cell that use information on DNA to make protein molecules

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17
Q

Name some features of bacterial cells

A
  • They always have a cell wall; this wall is not made of cellulose, but instead peptidoglycan
  • A partially permeable cell membrane is pressed tightly against the inside of a bacterial cell wall
  • They have cytoplasm and ribosomes
  • They do not have mitochondria or chloroplasts
  • They do not have a definite nucleus; instead, a circle of DNA. This is sometimes called a bacterial chromosome
  • They also have one or two small circles of DNA, called plasmids
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18
Q

What is a tissue?

A

A group of similar cells that work together to perform a particular function

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19
Q

What is an organ?

A

A group of different tissues that carry out a function together

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20
Q

What is an organ system?

A

Several organs that work together to perform a particular function

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21
Q

What is the formula for magnification?

A

Size of image
————————
Size of object

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22
Q

What is diffusion?

A

The net movement of particles down a concentration gradient.

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23
Q

What is osmosis?

A

The diffusion of water molecules through a partially permeable membrane

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24
Q

What is meant by high water potential?

A

An area where there are a lot of water molecules—a dilute solution

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25
Q

What is meant by low water potential?

A

An area where there are not many water molecules—a concentrated solution

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26
Q

What is meant by water potential gradient?

A

A difference in water potential between the two areas

27
Q

Explain what happens to animal cells when they are placed in pure water (3 marks)

A

The cells burst because water enters by osmosis

28
Q

Why does a plant cell not burst in pure water?

A

Because the strong cell wall stops it from bursting

29
Q

What is meant by turgid?

A

A description of a plant cell that is tight and firm

30
Q

What is turgor pressure?

A

The pressure of the water pushing outwards on a plant cell wall

31
Q

What is meant by flaccid?

A

A description of a plant cell that is soft

32
Q

What is meant by plasmolysed?

A

A description of a cell in which the cell membrane tears away from the cell wall

33
Q

What is active transport?

A

The movement of molecules or ions against a concentration gradient using energy from respiration

34
Q

What are carrier proteins?

A

Protein molecules in cell membranes that can use energy to change shape and move ions or molecules into or out of a cell

35
Q

What are some examples of carbohydrates?

A

Starch, cellulose and sugar.

More specific examples include: Glucose, etc.

36
Q

What are the linked-together glucose molecules in animals called?

A

Glycogen; it is used as an energy store in animal cells

37
Q

What is starch?

A

A carbohydrate that is used as an energy store in plant cells

38
Q

How can we detect the presence of starch?

A

By using iodine solution; it turns from brown to blue-black if starch is present

39
Q

Most sugars can be detected by _____________________

A

Benedict’s solution

40
Q

What happens to Benedict’s solution when heated with reducing sugars?

A

It changes from blue to orange-red.The colour change is gradual, so the blue solution becomes green and yellow before finally turning orange-red.

41
Q

What are fats?

A

Lipids that are solid at room temperature

42
Q

What are oils?

A

Lipids that are liquid at room temperature

43
Q

What are lipids?

A

They are substances containing carbon, hydrogen and oxygen that are used as energy stores in organisms. They are also insoluble in water.

44
Q

What are amino acids?

A

The building blocks of protein

45
Q

What are some of the functions of proteins in organisms?

A
  • Antibodies, which help protect the body against pathogens.
  • Enzymes
  • Haemoglobin
  • Forming cell membranes
  • Keratin: the protein that forms hair and fingernails
46
Q

DNA is made of smaller molecules called __________________

A

Nucleotides

47
Q

What is a base in DNA?

A

One of the components of DNA; there are four bases, A, C, G, and T, and their sequence determines the proteins that are made in a cell

48
Q

What is complementary base pairing?

A

The way in which the bases of the two strands of DNA pair up; A always with T, and C with G

49
Q

Vitamin C is tested using ______________

A

DCPIP (Dichlorophenolindophenol)

50
Q

What is a catalyst?

A

A substance that increases the rate of a chemical reaction and is not changed by the reaction

51
Q

What is an enzyme?

A

Proteins that are involved in all metabolic reactions, where they function as biological catalysts

52
Q

What does an amylase do?

A

Catalyses the breakdown of starch to maltose

53
Q

What does protease do?

A

Catalyses the breakdown of protein to amino acids

54
Q

What does catalase do?

A

Catalyses the breakdown of hydrogen peroxide to water and oxygen

55
Q

The names of enzymes often end in -ase. Using this, name the enzyme that catalyses the breakdown of carbohydrates, lipids, and maltose.

A
  • Carbohydrases
  • Lipases
  • Maltase
56
Q

The substance that an enzyme changes is called _______________

57
Q

Each enzyme has molecules with a very specific shape. The enzyme molecule has a ‘dent’ in it called ____________________

A

Active site

58
Q

What is the photosynthesis equation?

A

———————————-sunlight
and
chlorophyll
carbon dioxide + water———> glucose + oxygen

6CO2 + 6H2 —> C6H12O6 + 6O2

59
Q

What are vascular bundles?

A

Collections of xylem tubes and phloem vessels running side by side, which form the veins in a leaf

60
Q

What is the epidermis?

A

The outer layer of tissue on a plant

61
Q

What is the cuticle?

A

A thin layer of wax that covers the upper surface of a leaf

62
Q

What is the palisade mesophyll?

A

The layer of cells immediately beneath the upper epidermis, where most photosynthesis happens

63
Q

What is the spongy mesophyll

A

The layer of cells immediately beneath the palisade mesophyll, where some photosynthesis happens; this tissue contains a lot of air spaces between the cells

64
Q

What are stomata?

A

Openings in the surface of a leaf, most commonly in the lower surface; they are surrounded by pairs of guard cells, which control whether the stomata are open or closed. Guard cells are the only cells in the epidermis that contain chloroplasts

Ayyan's Handy Materials (4 decks)

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