Chapter 3 Flashcards
What animals are endothermic?
endothermic= (of an animal) dependent on or capable of the internal generation of heat.
- Mammals and birds
Both ____________ and ______________ cells use ATP
molecules to supply energy for their cellular
work.
prokaryotic, eukaryotic
- . In eukaryotic cells, most of the ATP is produced by mitochondria
Metabolism is
the sum of all chemical reactions in a cell or organism
- anabolic (making bonds) and catabolic (breaking bonds)
Japanese macaques
aka snow monkeys, expend a significant amount of energy to keep warm in their snowy environment. They forage for food to supply this energy
Work is performed when…
energy is used to move an object against an opposing force, such as friction or gravity.
- Ex, it takes energy to link amino acids into a chain to form a protein, or to pump sucrose across a cell membrane
Energy is
is the capacity to do work
- Each form of energy can be converted to other forms of energy
- during the process of photosynthesis, light
energy from the Sun is converted to chemical energy (stored in sugar) by organisms
Most living organisms obtain energy in one of two ways:
1) by obtaining it directly from the Sun through photosynthesis,
2) by consuming energy-rich molecules within food
webs that began with photosynthesis
All energy exists in one of two states: List them
kinetic energy
potential energy
kinetic energy is
the energy of motion –> anything moving like ions are ex of KE
- The KE that is present in movement is useful cuz it can perform work by making other objects move
Potential energy is
the stored energy that an object possesses as a result of its position relative to other objects or to its internal structure
Chemical potential energy
- stored in the electrons & protons that make up atoms & molecules. –> The electrons r often involved in chemical bonds.
- Released or absorbed during chemical reactions.
- stored in food molecules like glucose.–> When food molecules r broken down, usable energy is released to power cellular work.
A bond results when…
electrons are simultaneously experiencing a force of
attraction to protons in the nuclei of two atoms.
Gravitational Potential Energy
Related to an object’s position (e.g., a cyclist at the top of a hill or a diver on a platform).
- Results from Earth’s gravitational pull & the object’s height
When work is done, energy is…
transferred from one body or place to another.
Gravitational Potential Energy to Kinetic Energy: The Diver Example
a diver about to dive from a platform also has PE due to the force of gravity from Earth & her height above the surface of the H2O.
- The diver gains PE as her muscles work to climb the ladder & reach the top of the platform.
- When work is done, energy is transferred from one body or place to another.
- When she dives from the platform, the diver’s speed increases & she gains KE.
- She also loses PE as the distance between her & the water surface decreases
- Thus, as the diver plunges toward the H2O, some of her PE is converted to KE
The First Law of Thermodynamics
- AKA the law of energy conservation
The total amount of energy in any closed system is constant. Energy cannot be created or destroyed; it can only be converted from one form to another. If a physical system gains an amount of energy, another
physical system must experience a loss of energy of the same amount
Plants as Energy Transformers
Green plants convert sunlight into chemical energy through photosynthesis. –> Plants capture light energy from the Sun & convert it into chemical PE.
- This energy is stored in carbohydrates & other energy-rich molecules within plant cells.
- The chemical energy in plants is passed to organisms that eat them.
- Living Organisms: Convert the chemical energy from plants into other forms of energy –> Woodland caribou consume plant material, converting the plant’s chemical energy into mechanical energy to power muscle movement.
Conversion of energy from one form into another depends on…
the breaking & forming of chemical bonds in a chemical reaction.
- During a chem reaction, amount of PE that’s available changes
Potential Energy in Electrons (AKA Chemical PE)
- PE of e- depends on their location with respect to nucleus (+vely charged)
- farther away e- from the nucleus= more PE energy they have
–> The PE of e- increases when they absorb energy, move farther from
the nucleus, and reach an “excited” state. - unlike the diver being pulled by Earth’s gravitational force, there is not just one source of attraction; there r many sources, from many different atomic nuclei varying in their forces of attraction
Making & Breaking Bonds: When is energy absorbed? When is it released?
During chem reaction, some bonds between atoms in reactant molecules must be broken, & new bonds form between atoms in product molecules
- For bonds to break in reactant molecules= energy must be absorbed cuz energy is required to pull an e- away from an atom
- bonds are formed between the atoms of product molecules= energy is released.
–> Ex, combustion involves both the absorbing & releasing of energy
Chemical reactions & change in electron PE
- As bonds break and new bonds form, the positions of some electrons in the atoms
change. –> The change in PE of these electrons accounts for the change in energy during a chem reaction. - Breaking bonds=e- pulled away from nucleus=requires energy but increases the electrons’ PE
- Making bonds= e- move closed to the nucleus of another atom and release energy
- The released energy can be converted to different forms –> light & thermal energy from a burning candle is the result of electrons involved in bond formation.
Bond energy is
measure of the strength or stability of a covalent bond.
-measured in units of kilojoules per mole (kJ/mol) & is equal to the amount of energy absorbed/ mole when the bond between atoms is broken & is equal to the amount of energy released/ mole when the same bonds form.
- The energy needed to break a bond reflects the relative strength of the bond
A mole is
AKA Avogadro’s number,
a standard quantity equal to about 6.022x10^23.
- used in chem when considering # of extremely small particles.
Bond energy values are given as averages bcuz
bcuz actual bond energies vary depending on the other atoms in the molecules
- Ex, the bond energy of the O-H bond will vary depending on what other atoms the O forms a bond with.