energy in biology

Question 1

what are the different forms of energy?

Answer 1

• light
• chemical
• electrical
• nuclear
• heat
• mechanical
• kenetic energy(movement)
• potential energy(stored)

Question 2

how many calories are in each type of food per gram?

Answer 2

protein- 4kcal/g
fat- 9kcal/g
carbohydrate- 4kcal/g
alcohol- 7kcal/g

Question 3

what is the name of the study of energy transformations?

Answer 3

thermodynamics

Question 4

whats the first law of thermodynamics?

Answer 4

energy can neither be created or destroyed

energy can only be changed from one type to another

Question 5

what happens to the energy not available for work?

Answer 5

it is released as heat, this increases the entropy of the system (s)

Question 6

what is entropy (s)?

Answer 6

degree of randomness in any system

Question 7

explain what high and low entropy means?

Answer 7

high entropy- gas, low energy, unordered and messy

low entropy- crystal, high energy level, highly organised

Question 8

what is the second law of thermodynamics?

Answer 8

the universe tends towards disorder

all processes must increase the total entropy of the universe

Question 9

what increases entropy?

Answer 9

heat

Question 10

is entropy higher or lower in cells and why? and is the energy level higher or lower in cells?

Answer 10

the entropy is lower in the cell than its building blocks
-the energy level is higher as the cells need to gain energy from oxidising “foodstuff” molecules, the release of heat and CO2 into the cell increases the entropy

Question 11

what is enthalpy H?

Answer 11

it is its energy content or heat content

Question 12

when can chemical reactions occur?

Answer 12

-when there’s negative delta H and positive delta S

Question 13

is delta G positive or negative when a reaction happens spontaneously?

Answer 13

it is negative as energy is released so you dont need to provide the reaction with any extra

Question 14

how do cells manage energy resources?

Answer 14

they do it by energy coupling which is the use of an exergonic process (ATP hydrolysis) to drive an endergonic one. overall they are exergonic so they release energy

Question 15

what is the energy-barrier to chemical reactions and why is it needed?

Answer 15

its when reactions occur, the energy level must be raised to the transition state to prevent chemical reactions from occurring. its achieved by the action of enzymes

Question 16

describe the features of the transition state?

Answer 16

• it has a higher energy level than both the reactants and the products
• its the least stable species of the reaction pathway
• the free energy between the reactant and the transition state is called the activation energy
• enzymes speed up reactions by providing an alternative route past the transition state
• catalysis is the specific stabilisation of the transition state of a reaction

Question 17

what are the properties of a catalyst?

Answer 17

-lowers the activation energy
-speeds up chemical reactions
-isnt used up in the reaction
doesnt affect the equlibrium