BIO 110 exam 3

Photosynthetic organisms and animals release energy for metabolism by breaking down organic compounds through which of the following processes?

Aerobic cellular respiration

nitrogen fixing microbes het nitrogen from

N2

Which of the following is made during the light-dependent stages of photosynthesis?

NADPH

Select all forms of nitrogen that can be taken up and utilized by plants.

Nitrate Ammonium

Carbon fixation involves using the protons and electrons generated by the splitting of what molecule to convert CO2 into organic matter?

H2O

After absorbing the energy from light, chlorophyll in the reaction center becomes

a strong electron donor

In plants, each photosystem is a network of chlorophyll _____ molecules, accessory _____ and associated proteins.

a; pigments, carotenoids, or chlorophyll

The first step in the conversion of light energy into chemical energy by the reaction center is

absorption of a photon of light by chlorophyll in the reaction center.

The rate of an exergonic reaction can be increased by lowering the _______energy required to destabilize chemical bonds in the reactants.

activation

________ energy is the energy required to destabilize existing chemical bonds and initiate a chemical reaction.

activation

Microbes convert urea to __________which can be utilized as a source of nitrogen by plants.

ammonia

plants get nitrogen from

ammonia and nitrate ions

In a photosystem, the _____ complex captures light energy and passes it to the ______center where electrons are transferred out of the photosystem.

antenna, reaction

______ harvest light or chemical energy and use the energy to synthesize carbon compounds from CO2.

autotrophs

Which organisms make atmospheric nitrogen accessible to plants and algae?

bacteria

Photosynthetic organisms acquire ________ ________ from the atmosphere and incorporate it into biomass via photosynthesis.

carbon dioxide

The most important carbon-containing compound in the abiotic environment of ecosystems is

carbon dioxide

The formation of organic molecules from carbon dioxide is called

carbon fixation

The first two stages of photosynthesis require light and are commonly known as the light- __________ reactions.

dependent

What is the term for a community of organisms and the abiotic environment that affects them?

ecosystem

In the reaction center which of the following excited subatomic particles are transferred to an acceptor?

electrons

A reaction that requires an input of energy is said to be a(n) ______ reaction

endergonic, non-spontaneous

When a channel protein or carrier protein assists in diffusion, which of the following is observed?

facilitated diffusion

True or false: When a lion eats a giraffe, it both creates and adds new potential energy to its body.

false

Exergonic reactions have a(n) ________ change in free energy, and endergonic reactions have a(n) _________change in free energy.

negative, positive

Nitrogen fixation uses _________ gas as a substrate, while denitrification produces it.

nitrogen

Some prokaryotes can convert atmospheric ________ to ammonia

nitrogen

Which of these chemical elements is often the most limiting in ecosystems?

nitrogen

The synthesis of nitrogen-containing compounds from atmospheric N2 is called

nitrogen fixation

Select all compounds in which nitrogen is found.

nucleic acids and proteins

plants, algae, and cyanobacteria are examples of what

photoautotrophs

Almost all photosynthetic organisms capture light using

photosystems

Photosynthetic pigments in the chloroplast are organized into distinct clusters known as

photosystems

In chloroplasts, several dozen of these kinds of molecules help comprise a light harvesting complex:

pigments

Molecules that can absorb light in the visible range are called

pigments

herbivores het nitrogen from

plants and algae

The major barrier to crossing a biological membrane is the hydrophobic interior of the membrane that repels what kind of molecules?

polar molecules

In a green plant, the majority of photosynthesis takes place in __.

the leaves

The excited chlorophyll in the reaction center transfers its electron to

the primary acceptor

What is ultimately the main source of energy for almost all living cells on Earth?

the sun

Which of the following (choose all that apply) are necessary for carbon fixation in the Calvin cycle?

ATP and NADPH

Which of the following are the two components of a photosystem?

An antenna complex. A reaction center.

Which of the following are chloroplast membranes?

An inner membrane An outer membrane The thylakoid membrane

Why are the cyclic reactions in carbon fixation also referred to as light-independent reactions?

Because they can occur whether or not light is present.

What term best describes the movement of elements between living and nonliving systems?

Biogeochemical cycles

Select all systems involved in the cycling of chemical elements in ecosystems.

Biological Geological

Which of the following are the three stages of photosynthesis in plants?

Capturing energy from the sunlight Making ATP and NADPH Using ATP and NADPH to produce organic compounds from CO2

In the carbon cycle, both decaying organisms and aerobic cellular respiration release which of the following?

Carbon dioxide

Select all ways in which nitrogen gas may directly enter the atmosphere.

Denitrification by microbes Release of ammonia from the soil

Net movement of a substance from a region where it has a higher concentration to a region where it has a lower concentration is called which of the following?

Diffusion

Which statement about energy conversion is true?

During any type of energy conversion, some of the energy is lost into the environment as heat.

During photosynthesis, a chlorophyll in the reaction center loses its excited electron. How is that electron restored?

From a nearby weak electron donor.

Which of the following is another way to state the second law of thermodynamics?

Entropy increases.

Which of the following is TRUE concerning the number of each type of atom on Earth?

It is essentially fixed.

What is the first law of thermodynamics?

The first law states that energy cannot be created or destroyed.

What is nitrogen fixation?

The conversion of atmospheric nitrogen to a usable form

Select the statements that describe the free energy (G) change of a spontaneous reaction.

The free energy of the products is less than the reactants. There is a negative free energy change.

The third and final stage of photosynthesis is also known as which of the following?

The light-independent reactions

Select the true statements about endergonic reactions.

The products have a higher free energy than the reactants. Endergonic reactions have a positive change in free energy. Endergonic reactions are not spontaneous.

Which of the following membranes contains pigments in a green plant?

The thylakoid membrane

In which of the following is ATP used directly in active transport?

The transport of Na+ across the plasma membrane.

______ energy is a form of potential energy stored within the covalent bonds of molecules.

chemical

Because cells are too small to maintain significant internal temperature differences, cells rely on________ reactions rather than a _______ gradient to do work.

chemical, heat

Similar to a mitochondrion, a(n) _____________ contains an outer and inner membrane, with an intermembrane space between the two. Unlike a mitochondrion, it also contains chlorophyll-containing membranes called __________ membranes

chlorplast, thylakoid

All living things require which of the following, in order to carry out chemical reactions and thereby survive?

energy

In the light-harvesting complex of the chloroplast, it is excitation __________, not the electrons themselves, that pass from one pigment molecule to the next.

energy

The first law of thermodynamics states that the total amount of _________ in the universe remains constant.

energy

The third stage of photosynthesis is also called carbon ______

fixation

What is the term used to describe the energy of a system that is available to do work?

free energy

Although there is an abundance of nitrogen_______ in the atmosphere, most organisms are unable to use nitrogen in this form, and therefore the supply of nitrogen available to them is limited.

gas

When the concentration of a substance varies from one region to another, this substance is said to exhibit a concentration

gradient

During each energy conversion that happens in a living organism, some of the energy dissipates as

heat

________ is a general term that describes all organisms that obtain their nutrition by breaking down pre-made organic compounds.

heterotrophs

In general, energy transformations can proceed spontaneously when disorder

increases

spontaneous reactions happen when disorder ________

increases

How is the reaction center positioned in the membrane?

it is a transmembrane protein

Heat is what kind of energy

kinetic

hen the free energy change that occurs as a result of a chemical reaction is __________than zero, the reaction is spontaneous

less

The cyclic reactions in carbon fixation do not require which of the following?

light

The role of the______-harvesting complex is to directly absorb photons of light.

light

What is entropy?

measure of disorder in a system

In a leaf, the thick layer of cells that are rich in chloroplasts is called the

mesophyll

Heat is the random _____ of molecules

movement

Living organisms can convert the potential energy stored in chemical bonds into what other forms of energy?

potential energy in the bonds of new molecules electrical energy (electricity) kinetic energy light energy

The first stage of the thylakoid (or light-dependent) reactions is the

primary, photoevent

chemoautotrophs

prokaryotic microbes in deep sea water vents

The reaction center in chloroplasts is a transmembrane ______ pigment complex

protein

In a photosystem, chlorophyll a molecules are found in a matrix of

proteins

The chloroplast's _________contains enzymes needed to assemble organic molecules from CO2.

stroma

In a chloroplast, chlorophyll molecules that capture light energy are found in the internal, or inner membrane, which is also called the

thylakoid membrane

The internal membrane of the chloroplast is also known as the

thylakoid membrane.

True or false: Heat energy cannot be used by cells to do work.

true

Having two different linked photosystems in chloroplasts overcomes the limitations of anoxygenic photosynthesis by allowing the oxidation of

water

What is split during photosynthesis in plants resulting in the production of oxygen?

water