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Worksheetsunit 3
Total questions: 89
Worksheet time: 1hrs 16mins
Loss of order, or energy flow, results in death
Anabolic pathways are those that must consume energy to build complex molecules
Cofactors are proteins that assist in enzyme function
In some reactions, the end product can act as an inhibitor to an early enzyme in the same pathway
enzymes are proteins that catalyze reactions by raising the activation energy
the function of light in photosynthesis is to excite electrons in chlorophyll
oxygen, an input in photosynthesis, plays a vital role in the process
during the light dependent reactions, protons (H+) accumulate in the stroma creating a concentration gradient
in order for an organism to be classified as a photoautotroph it must have chloroplasts
photosynthesis captures energy from the sun and produces carbohydrates
(a) is defined as the ability to do work
_______ energy is associated with motion while ________ is stored energy
(a)
A concept known as ____ ______ can be used to determine the likelihood of reactions
(a)
_________ reactions release energy while __________ reactions absorbs energy
(a)
(a) are the cells that make up the interior tissue of a leaf
_____ is electromagnetic energy that is made up of particles of energy called _______
(a)
(a) are pores in leaves that allow for gas exchange
_____ wavelengths have high energy while ____ wavelengths have low energy
(a)
which of the following best describes the role of an enzymes active site
it stores the energy required for chemical reactions
it binds with substrate molecules, facilitating their conversion into products
it regulates the overall pH of the cell
it acts as a barrier, preventing substrate from binding the enzyme
enzymes play a crucial role in biological reactions by lowering the activation energy required for reactions to proceed. Which of the following best explains how an enzyme accomplishes this?
enzymes increase the temperature of the reaction environment, which speeds up the reaction
enzymes supply additional energy to the reactants, increasing the overall energy of the system
enzymes reduce the concentration of substrates, thereby increasing the likelihood of a reaction occuring
enzumes provide an alternative reaction pathway with a lower activation energy, allowing the reaction to proceed faster
a pharmaceutical company is developing a new drug designed to inhibit a specific enzyme involved in cancer cell metabolism. If the drug works by increasing the activation enery required for the enzume-catalyzed reaction, what effect would this have on the rate of the reaction?
the reaction rate would increase because the enzyme would become more active
the reaction rate would decrease because the enzyme would require more energy to catalyze the reaction
the reaction rate would remain unchanged because enzymes are not affected by changes in activation energy
the reaction rate would decrease because the drug would lower the concentration of substrates available to the enzyme
an enzyme activity can be significantly affected by pH levels. What is the primary reason that a change in pH can be affected enzyme activity?
pH changes can alter the enzymes active site, affecting substrate binding
pH changes can remove the substrates from the reaction
pH changes can increase the temperature of the environment
pH changes can decrease the concentration of products in the reaction
which statement best describes the relationship between energy input and living systems?
living system can function efficiently without any external energy input
energy input must exceed energy loss to maintain order and drive cellular processes
cellular processes that require energy release energy instead
energy is not necessary for the maintenance of life in highly ordered systems
in the absence of oxygen, how do cells continue to produce atp?
by using an alternative terminal electron acceptor in the ETC
by increasing the rate of oxidative phosphorylation
be fermenting glucose through pathways that regenerate nad+ for glycolysis
by bypassing the etc and directly phosphorylating adp to atp
a research team is designing a new enzyme variant to improve agricultural productivity by increasing the rate of photosynthesis in plants. The enzyme variant must withstand higher temperature to be effective in arid climates. Which modification should the team prioritize to prevent enzyme denaturation at high temperatures, while maintaining catalytic efficiency
increasing the enzyme's molecular weight to slow down its reaction speed
introducing disulfide bonds to stabalize the enzymes 3d structure
modifying the enzyme to have a larger active site to bind more substrates
reducing the enzymes surface area to decrease the absorption
enzymes such as lactase are essential for breaking down lactose in the digestive system. However, at temperatures above 60 degree, lactase becomes denatured and loses its ability to function. What is the primary reason why lactase loses its function at high temperatures?
the substrate is destroyed at high temperatures
the enzumes 3d structure is altered, preventing substrate binding
the enzymes becomes more reactive and breaks down too quickly
the concentration of lactose decreases at high temperatures
during the light-dependent reactions of photosynthesis, an electrochemical gradient is establishes across the thylakoid membrane. What is the significance of this gradient?
it directly powers the conversion of carbon dioxide into glucose
it drives the splitting of water molecules to produce oxygen
it provides the energy needed to reduce nadp+ to nadph
it is used by atp synthase to produce atp from adp and inorganix phosphate
energy transformation ________ the _______ (measure of disorder) of the universe
- when energy is converted from one form to another, some energy is lost as ____
- heat = ____ usable energy = disorganized
(a)
metabolism: the sum of all ________ ________ in a cell that transform energy and matter
(a)
metabolic pathways: series of linked chemical reactions that either _____ ____ complex molecules or _____ complex molecules
(a)
Catabolic pathways: pathways that ________ complex molecules; ________ energy.
Example: Cellular ___________
(a)
Anabolic pathways: pathways that _____ complex molecules from simpler compounds; _______ energy
For example: ____________
(a)
Adenine Triphosphate: molecule that organisms use as a source of energy to perform work
it is made up of: _______ (nitrogen base), ______ (sugar), (3)_________ groups
(a)
1. The process ATP + H₂O → ADP + Pᵢ is best described as:
A) A dehydration synthesis reaction
B) An endergonic hydrolysis reaction
C) An exergonic hydrolysis reaction
D) A phosphorylation reaction
2. The primary role of the phosphate group (Pᵢ) released during ATP hydrolysis is to:
A) Be immediately excreted as waste
B) Bind to and activate another molecule, making it more reactive
C) Directly provide electrons for redox reactions
D) Lower the activation energy of the reaction as an enzyme
How does phosphorylation "drive" an energy-needing reaction?
A) By breaking the high-energy bonds in the substrate
B) By decreasing the reactivity of the target molecule
C) By transferring energy and making a molecule more reactive
D) By acting as a catalyst to speed up all cellular reactions
ATP hydrolysis is an _________ process that _______ energy. The chemical equation for this reaction is: ATP + H₂O → ADP + Pᵢ.
(a)
The phosphate group released from ATP can be transferred to another molecule in a process called ___________. This phosphorylated molecule is now called a _______ ___________.
(a)
Phosphorylation makes the target molecule more (a) . This transfer of energy from ATP is used to drive energy-needing reactions in the cell
what do cells need energy for?
mechanical work
transport work
chemical work
cofactors: non-_______ molecules that bind to enzymes and assist enzyme function
- some are metallic ions (iron, copper, zinc, etc)
- others are small organic compounds called _________
- assist enzymes in catalysis and act as _________ ________ during reactions
(a)
__________: organelle for the l0cation of photosynthesis
- stomata: pores in leaves that allow ___ in and __ out
(a)
stroma: aqueous ________ fluid
- location for _____ _____ (light independent)
(a)
thylakoids: flattened sacs containing chlorophyll ________
- form stacks known as grana
- location for _____ _________
(a)
pigments: contain ________ that absorb _____ energy for photosynthesis
(a)
chlorophyll a is the _______ pigment; chlorophyll b and carotenoids are _________ pigments that expand the _______ light spectrum and and protect chlorophyll from damage
(a)
chlorophyll (a) a photon of light
1. What is the immediate result when a chlorophyll molecule absorbs a photon of light?
A) It gains a proton (H⁺).
B) An electron is boosted to a higher energy level (excited state).
C) It immediately splits a water molecule.
D) It releases energy as fluorescence.
2. Which of the following outcomes is considered "wasteful" from the perspective of photosynthesis, as it does not capture the light energy for chemical work?
A) The energy is transferred to a neighboring pigment molecule.
B) The excited electron is passed to an electron acceptor.
C) The electron falls back to its ground state, releasing heat and light.
D) The chlorophyll molecule becomes oxidized.
The process that initiates the light-dependent reactions of photosynthesis by creating a flow of electrons is:
A) The release of fluorescence.
B) The transfer of an excited electron to an electron acceptor.
C) The release of energy as heat.
D) The cyclic movement of an electron back to its ground state.
The three possible fates of an excited electron are:
It can fall back to its ground state, releasing energy as ____ and fluorescence.
The energy can be ___________ to a neighboring pigment molecule.
The excited electron itself can be passed to an ________ ________, which is the first step of the electron transport chain.
(a)
The only fate that directly leads to the conversion of light energy into chemical energy is the transfer of the excited electron to an ________ ________.
(a)
the light reactions: occur in the thylakoid membrane
- converts _____ energy to ________ energy (___, _____), which will later be used in Calvin Cycle
(a)
the light reactions begin when _____ is absorbed by chlorophyll a pigments in the ____________
(a)
Photosystem 2: ____
Photosystem 1: ____
(a)
Photosystem 2:
- p680+ is a strong oxidizing agent (it _____ electrons)
- p680+ replaces its lost electrons by taking electrons from _____, causing water to _____
(a)
ETC
- electrons will pass from PS 2 to PS 1 via proteins embedded in the membrane (___)
- electrons _____ ______ as it goes
- some of the released energy drives the _______ of _+ from the stroma into the thylakoid lumen
- an electrochemical gradient of _______ (H+) is establishes across the membrane (due to both the pumping of H+ and water splitting)
(a)
Photosystem 1:
- electrons are excited to a higher energy level by _________ more light energy
- electrons are transferred to NADP+ ________ it to _____
- the process of electrons being removed from water and passed from PS2 and PS1 before ending in NADPH is photophosphorylation
(a)
chemiosmosis
- H+ flows down its gradient, passing through atp synthase, driving ___ production from ADP + Pi (chemiosmosis)
- _____ and ___ head to the calvin cycle
(a)
Calvin Cycle:
- use ___ and _____ to produce carbohydrates (sugar:G3P) from ___
- for net synthesis of 1 G3P molecule, the cycle must take place _ times
(a)
3 phases of Calvin Cycle:
1. Carbon ________
2. _________
3. Regeneration of ____
(a)
phase 1: carbon fixation
- ___ is incorporated into the calvin cycle _ at a time (3 times total to produce 1 net G3P)
- each co2 attaches to a molecules of ____
- catalyzed by the enzyme _______
- this _____ CO2 (incorporates it into organic molecules) into 3-PGA
(a)
phase 2: reduction
- atp and nadph are used to convert ____ into ___
- ___ phosphorylates ____ into an intermediate
- _____ reduces the intermediate (donates electrons to it) forming ___ (a sugar)
- 6 molecules of g3p are formed, but only one is counted as a net gain
- the other 5 g3p molecules are used to regenerate RuBP
(a)
Phase 3: Regeneration of RuBP
- 5 G3P molecules are used to regenerate 3 molecules of RuBP
- uses 3 ___ for regeneration
- cycle is ready to take in ___ again
(a)
light reactions:
converts solar energy to chemical energy (___ + _____)
- this powers the production of carbohydrates from carbon dioxide in the calvin cycle
(a)
Calvin Cycle
- uses _____, ___, and ___
- produces a 3c _____ G3P
(a)
cellular respiration:
cells harvest ________ energy stored in organic molecules and use it to generate ___
(a)
starch is broken down in _______
- catabolic breakdown of glucose
- the _________ of glucose transfers e- to a _____ energy state, releasing energy to be used in ___ synthesis
(a)
stages of cellular respiration:
1. __________
2. Pyruvate _________ (link reaction)
3. ______ acid cycle (krebs cycle)
4. _________ phosphorylation (ETC and chemiosmosis)
(a)
glycolysis:
- starting point of cellular respiration
- occurs in the _______
- splits _______ (6c) into 2 _________ (3c)
(a)
2 stages of Glycolysis:
1. Energy __________ stage: the cell uses ___ to ____________ compounds of glucose
(a)
2 stages of Glycolysis:
2. Energy ______ stage: energy is ________ by substrate level _______________
- the net energy yield per 1 glucose:
2 ATP
2 NADH
(a)
Glycolysis Summary | starting materials:
_______, ___, ___+, ___ + _i
(a)
Glycolysis Summary | End Products:
2 ________, 2___, 2____
(a)
Pyruvate oxidation:
if ______ is present, the pryruvate enters a mitochondrion
- pyruvate is ________ into ______ ___
- Acetyl coA is used to make _______ in the citric acid cycle (kreb cycle)
- ___ is released as waste
- electrons are transferred to carriers (____)
(a)
Pyruvate oxidation summary | starting materials:
2 ________, ________ _, ___+
(a)
Pyruvate oxidation summary | End products:
2______ ___, __2, 2____
(a)
citric acid (Krebs) cycle:
occurs in the _____________ matrix
turns ______ coA into _______ (citric acid)
- releases __2
- ___ synthesized
- electrons are transferred by ___+ and ___
- ____ and ____2 will then carry high energy electrons to the ___
(a)
citric acid (krebs) cycle summary | starting materials
- 2 acetly ___
- ___+
- ___
- ___ + _i
(a)
citric acid (krebs) cycle summary | end products:
- 4 __2
- 6 ____
- 2 ____2
- 2 ___
(a)
oxidative phosphorylation
consist of:
___
____________
(a)
etc
the etc is located in the inner membrane of the mitochondria
- consists of a collection of _______ carriers (proteins) embedded in the membrane
- ____ and ____2 (from _____ cycle) bring electrons to the etc
- the electrons are shuttled down the etc in a series of redox reactions until they the final electron acceptor, ______
- as the elecrons are transferred through the etc they move from a highet to lower energy level
- some of the released energy is used to ____ H+ intp the membrane space, fprming an _______________ _______ of protons H+
(a)
chemiosmosis:
- H+ ions flow down their gradient bak into the matrix through atp synthase
- drives the formation of (a) from adp + Pi
- the cristae increases the surface area for the eaction to occur
- allows more atp to be synthesized
- produces about 26-28 atp per glucose
Oxidative Phosphorylation summary | starting materials
____
____2
_2
___ + _i
(a)
Oxidative Phosphorylation summary | end products
___+
___
_2_
__ - __ ATP
(a)
Anaerobic respiration: generates ___ using an ___ in the absense of ______
- the final electron acceptors: _________ or ________
(a)
Fermentation: generates ATP without an ___ (fermentation does not directly make atp, but recycles nad+ which allows glycolysis to continue to directly create ATP)
- extension of glycolysis
- recycles ___+
- occurs in the _______
- no oxygen
- _______ and ______ acid fermentation
(a)
Alcohol Fermentation: ________ is converted into _______ (CO2 is released as waste)
(a)
Lactic Acid Fermentation: pyruvate is reduced directly by ____ to form _______
(a)
