Term 1

Question 0

What is metabolism?

Answer 0

Chemical reaction and cell repairs.

Question 1

What is cellular organisation?

Answer 1

The basic function and structure of a cell.

Question 2

What is homeostasis?

Answer 2

Self-regulating control mechanisms.

Question 3

What is heredity?

Answer 3

A genetic system based on the reproduction of DNA.

Question 4

What is a prokaryote?

Answer 4

• Prokaryotic cells have no nucleus.
• Their genetic material is found in a region called the nuclear area, but is not seperate do by membrane.
• Generally smaller than eukaryotes.
• Usually unicellular organisms (bacteria).

Question 5

What is a eukaryote?

Answer 5

• Eukaryotes are categorised by having their genetic material contained by a nuclear membrane.
• Much larger than prokaryotic cells.
• More complex because of their membrane bound organelles.
• Examples: fungi, animals, plants, protistans.

Question 6

What is a protist?

Answer 6

A protist is a large diverse group of eukaryotic organisms which belong to the kingdom Protista.

Question 7

What are the two classifications of a eukaryote?

Answer 7

They can be;

• Unicellular organisms (e.g. the protistans)
• Multicellular organisms (e.g. plants)

Question 8

What is a producer, consumer and an autotroph?

Answer 8

A producer produces: plants.
A consumer consumes: birds.
An autotroph makes their own energy using light or chemical energy.

Question 9

What is a heterotroph?

Answer 9

A heterotroph is an organism which is dependant on complex organic substances for nutrition because it cannot synthesise its own food; e.g. dogs, humans.

Question 10

What is cell specialisation?

Answer 10

• Cells vary in their shape and contents to match their environment and biological function.
• Cells of unicellular organisms remain quite unspecialised and must carry out a range of biological functions.
• Multicellular organisms exhibit much greater specialisation; each cell may perform limited tasks.

Question 11

What is osmosis?

Answer 11

• Osmosis is a specific type of cell diffusion. Diffusion is the movement of water across a selectively permeable membrane, from an area of high concentration to low.
• Where solution concentration is greater, water is less.
• Where solution concentration is low (dilute), water is greater.
• The water diffuses from the dilute solution to the concentrated one.
• Water is the solvent.
• Dissolved substances are the solute.

Question 12

What are the 5 factors affected by diffusion and osmosis?

Answer 12

• Temperature
• Surface Area
• Particle Size
• Diffusion Medium
• Concentration Gradient

Question 13

What is a hypertonic, hypotonic and isotonic solution?

Answer 13

Hypertonic- Solution with a higher concentration of solute than water (plasmolysis/flaccid cell).
Hypotonic- Solution with a lower concentration or solutes (turgid cell).
Isotonic- Solutions with the same concentration.

Question 14

What is water potential?

Answer 14

The tendency for water molecules to enter or leave a cell by osmosis. Dissolving a solute into pure water lowers the water potential (makes it more negative).
Water always diffuses from regions of less negative WP to more negative WP (higher water potential to lower).

Question 15

What is active transport?

Answer 15

• Active transport processes require energy expenditure because materials must be moved against their concentration gradient. Transport proteins harness ATP to pump molecules from a low concentration to a high.
• Active transport is performed by specific carrier proteins in the membrane.

Question 16

What is cytosis?

Answer 16

• A form of active transport, involving the formation of membrane bound vesicles or vacuoles.
• Most cells carry out various forms of cytosis, including:
  
  • Endocytosis
  • Exocytosis

Question 17

What is invagination and evaginated?

Answer 17

• Regions of the plasma membrane become infolded (invagination) or outfolded (evaginated) to transport substances across the membrane.

Question 18

What is Endocytosis?

Answer 18

The incorporation of substances from outside the cell into the cell as a membrane bound vesicle.

Question 19

What happens during Endocytosis?

Answer 19

The plasma membrane invaginate’s around the ,ole ile to be transported into the cell.

Question 20

What are the 3 forms of Endocytosis?

Answer 20

Phagocytosis: The engulfment of solid particles.
Pinocytosis: The engulfment of liquid particles.
Receptor mediated: Engulfment of specific particles according to membrane receptors.

Question 21

What is Exocytosis?

Answer 21

Exocytosis releases substances from inside the cell to outside.

Question 22

How does Exocytosis occur?

Answer 22

Occurs by a fusion of a vesicle membrane with the plasma membrane. The vesicle content are then released outside of the cell.

Question 23

Why is diffusion effective for smaller organisms?

Answer 23

Because a smaller organism has a large surface area relative for it’s volume, therefor it diffuses faster.

Question 24

What happens when an organism gets larger?

Answer 24

The surface area decreases- and ceases to be an effective way to exchange materials through diffusion.

Question 25

What happens as a cell size increases?

Answer 25

• It’s volume increases at a faster rate than its SA.
• There is less SA, therefor the SA to volume ratio decreases.
• Large materials have trouble exchanging materials at rates adequate to meet demands.

Question 26

What is an enzyme?

Answer 26

• Enzymes are molecules that act as catalysts to speed up biological reactions.
• Enzymes are not consumed during the biological reaction.
• Most enzymes are proteins.

Question 27

What does an enzyme do?

Answer 27

Enzymes can break a single structure into smaller components or join two or more substrate molecules together.

Question 28

What is pepsin?

Answer 28

Pepsin Is a stomach enzyme used to break protein down into peptides. Works at a very acidic pH (1.5).

Question 29

Where do the enzyme and substrate bind?

Answer 29

They bind at the active sight. Substrate modification occurs at the active sight. When a substrate binds to an enzymes active sight, an enzyme-substrate complex is formed.

Question 30

What are the 3 steps in the enzyme lock and key model?

Answer 30

1. The substrate is drawn to the enzymes active sight.
2. The substrate must be compatible with the enzyme in order to fit and react. The enzyme reacts with the substrate and breaks it.
3. Enzyme modifies the substrate and releases it.

Question 31

What the induced fit model?

Answer 31

More recent studies have shown that the process is much more likely to involve an induced fit. The enzyme or the reactants (substrate) change their shape slightly in order to bond with a wider range.

Question 32

What is a catalyst?

Answer 32

• Enzymes are catalysts- they make it easier for a reaction to take place.
• Catalysts speed up the reactions, thus lowering the activation energy needed for the reaction to take place.

Question 33

What is a catabolic reaction?

Answer 33

Catabolic reactions involve the break down of larger molecules into smaller components, with the release energy.

Question 34

What are some types of catabolic reactions?

Answer 34

Digestion: Break down of large food molecules.

Cellular respiration: Oxidative break down of fuel molecules such as glucose.

Question 35

What is an anabolic reaction?

Answer 35

In anabolic reactions, smaller molecules are joined to form larger ones.

Question 36

What effect does temperature have on enzyme reactions?

Answer 36

For most plant and animal enzymes, there is little activity in low temps. Enzyme activity increases with temperature, until the temperature is too high to function. At this point, enzyme denaturation occurs.

Question 37

What effect does pH have on enzyme reactions?

Answer 37

Enzymes can be effected by enzyme pH. Enzymes are found in very diverse pH conditions, so they must be suited to perform in the specialist environment.
E.g. Pepsin is a stomach enzyme and has an optimal working pH of 1.5, which is suited for the very acidic conditions of the stomach.