Biology Chapter 8


A process by which certain groups of organisms capture energy from sunlight and convert this solar energy into chemical energy that is initially stored in a carbohydrate (sugar).


Pore-like openings in leaves that allow gases (CO? and O?) and water to diffuse in and out of the leaves.


The organelles within plant and algae cells that are the sites of photosynthesis.


Located inside the chloroplasts, a network of chloroplasts membranes that are active in photosynthesis.


The liquid material of the chloroplast that Thylakoids are immersed in.


The primary pigment active in plant photosynthesis.


Organized complex of molecules within a thylakoid membrane that, in photosynthesis, collects solar energy and transforms it into chemical energy.

Reaction Center

A pair of special chlorophyll A molecules and associated compounds that first receive the solar energy from photosystem pigments and then transform this solar energy into chemical energy.

Electrons; carbon dioxide; carbohydrate (a sugar)

In Photosynthesis, the power of the sun is used to boost the energy of ________ that are derived from water and bring them together with both a low-energy sugar and _______ from the atmosphere, thus producing and energy-rich ________, meaning food.

Chloroplasts; leaves; chlorophyll A

In plants, photosynthesis takes place within the organelles called ______, which are found most abundantly in certain cells that make up the interior portions of _______. Pigments within the membranes of these organelles, in particular a pigment called __

Light reactions; primary electron acceptor; energy state

Photosynthesis can be divided into two major sets of steps. In the first set, known as the _______, absorbed solar energy moves electrons derived from water in two ways: (a) physically to a molecule called a _______ and (b) metaphorically to a higher ____

Calvin cycle

The set of steps in photosynthesis in which energetic electrons are brought together with cardon dioxide and a sugar to produce an energetic carbohydrate.


First step in Calvin cycle, a gas being incorporated into a organic molecule.

Electrons; NADPH; ATP; Oxygen

The energy acquired in the light reactions takes two forms: energetic _______ stored in the carrier _______ and energy stored in the energy transfer molecule _______. An important by-product of the light reactions is the _______ produced when water is spl

Calvin or C3

The energy from the light reactions is used to power the second major set of steps in photosynthesis, the _______ cycle.

Sugar; Atmosphere; electrons; ATP

In the Calvin cycle, an energy-poor _______ is brought together with carbon dioxide from the _______, and the resulting product is energized with _______ derived from the light reactions. This process is powered by the ______ produced in the light reactio


A process in which the enzyme rubisco reduces carbon fixation in photosynthesis by binding with oxygen instead of with carbon dioxide.


An enzyme that allows organisms to incoporate atmospheric carbon dioxide into their own sugars during the process of photosynthesis.

C4 Photosynthesis

Carbon dioxide is first fixed to a four-carbon molecule and then transferred to special cell's (bundle-sheath cells) in which the calvin cycle is undertaken.

CAM photosynthesis

Undertaken by plants in hot, dry climates, in which carbon fixation takes place at night and the Calvin cycle occurs during the day.

low-energy sugar; carbon; oxygen; photorespiration

The enzyme rubisco brings together the _______ (from the plant) and _______ (from the atmosphere), creating the product that moves through the Calvin cycle. Unfortunately, rubisco also has an affinity for binding with ______, a process known as _______.

Warm-weather; C4

An evolutionary adaption to this process, found in plants that thrive in _______ climates, is _______ photosynthesis, in which carbon dioxide is first fixed to a four-carbon molecule and then transferred into cells that carry out the Calvin cycle.

CAM; at night; during the day

Plants that exist in climates that are both hot and dry employ a variation on photosynthesis, _______ photosynthesis, in which carbon dioxide is brought into the plant only ________, while the Calvin cycle is carried out only _______.


In photosynthesis, energy from the sun is being ______ while in the cellular respiration looked at in Chapter 7, energy is being _______.
A. turned into light...turned soley into heat.
B. entirely lost to heat...stored as ADP.
C. stored in carbohydrates..


Stomata are the _____ on leaves that serve not only to let water vapor out but to let _____ in.
A. proteins...oxygen
B. cilia...oxygen
C. outer cell layer...sunlight
D. stems...carbon dioxide
E. pores...carbon dioxide


Two important products of the light reactions in photosynthesis are:
A. electrons, oxygen
B. electrons, carbon dioxide
C. chloroplasts, carbon dioxide
D. rubisco, oxygen
E. rubisco, carbon dioxide


You are Biologist. On a bright summer day, while studying the rate of photosynthesis in a desert plant, you discover that its stomata are closed, yet it is producing ATP. This plant must be carrying out:
A. photorespiration
B. the C3 cycle
C. the C4 pathw


Most plant photosynthesis occurs in the _______ of leaves.
A. upper epidermal cells
B. lower epidermal cells
C. petioles
D. stomata
E. mesophyll cells


The essential product of photosynthesis is:
B. rubisco enzyme
C. G3P sugar
D. plant structural proteins
E. carbon diozide


The electrons boosted to a higher energy level in photosystem II are derived from the splitting of _______, which results in the release of the by-product _______.
A. carbon dioxide...ATP
B. water...oxygen
C. NADPH...carbon dioxide
E. rubisco...oxygen


The enzyme rubisco is important because:
A. it aids in splitting water molcules, thus yielding oxygen.
B. it powers the light reactions through use of ATP.
C. it brings together carbon dioxide from the atmosphere with the plant's own sugar.
D. it is photo

Yes, plants are as dependent on cellular respiration as we are. Plants make food, carbohydrates, in photosynthesis. But just as we have to break down the food we eat to get the energy transferred to ATP, so plants have to break down the good they make to

Since plants capture energy through photosynthesis, do they need to carry out cellular respiration as well? Why or why not?

The sunlight that makes it to the Earth's surface is composed of a spectrum of energetic rays that range form very short ultraviolet rays, through visible light rays, to the longer and less-energetic infrared rays Photosynthesis is driven by part of the v

Sunlight reaching Earth is composed of a spectrum of energetic rays. Describe the rays that make up this spectrum. Which portion of the spectrum drives photosynthesis?

A photosystem includes several hundred antennae pigments consisting of both chlorophyll a and accessory pigments. These molecules collect solar energy and pass it along to another part of the photosystem, the reaction center. The reaction center consists

What are the component parts of a photosystem?

The C4 plant would be likely to grow more rapidly in a warm weather climate. Warm weather causes all plants to close their stomata for longer periods of time as a means of preserving water. When their stomata are closed, plants lose access to atmospheric

Which plant would you expect to grow more rapidly in a warm-weather climate - a C3 plant or a C4 plant? Explain.

The ATP is used to power the steps of the Calvin cycle. ATP is used in two separate steps during the cycle; once when 3-PGA is being energized by electrons produced by the light reactions and again when G3P is being transformed into the RuBP that begins t

The text notes that the fall of electrons between photosystems II and I provides energy used to produce ATP. What is the ATP used for?


What can exist in great abundance in the mesophyll cells of plant leaves?

blue; red; green; green

The energy for photosynthesis comes mostly from various ___ and ___ wavelengths of visible sunlight that are absorbed by pigments in the chloroplasts.Plants are ____ because they reflect the ____ portion of the visible light spectrum.


Plant leaves contain microscopic pores called _____ that can open and close, letting carbon dioxide in and water vapor out.


Thylakoids stacked on top of one another

thylakoid membranes

The ______ ______ are the place where photosynthesis starts with the absorption of sunlight.

a pigment

A compound that strongly absorbs certain visible wavelengths of light is called

chlorophyll a

Thylakoid membranes contain a pigment called ______ that is the primary pigment active in plant photosynthesis. ________ is aided by accessory pigments which aid ________ by absorbing solar energy and passing the absorbed energy along to chlorophyll .

The Light Reactions
The Calvin Cycle

These are the two primary stages to photosynthesis

light reactions; Thylakoid membranes

The first stage of photosynthesis is called the ____ and takes place in ______

light reactions

electrons derived from water are energetically boosted by the power of sunlight. These electrons physically move in this process: they are passed along through a series of electron carriers, ending up as part of the electron carrier NADPH, which carries t

Calvin cycle

What stage it it where the electrons are brought together with carbon dioxide and a sugar.The product of this stage is a high-energy sugar (food) in a process powered by ATP that is produced in the previous stage of photsynthesis

Calvin cycle; Stroma of the chloroplast

The second stage of photosynthesis is the _____ and takes place in _____

primary electron acceptor; primary electron receptor

The first recipient of solar energy is the ______ The movement of electrons from the reaction center to the __________ is a redox reaction.

photosystems II and I

In its first stage, photosynthesis works through a pair of molecular complexes _______ ________; are composed partly of antennae molecules´┐Żchlorophyll and some accessory molecules´┐Żthat absorb and transmit solar energy.

Water; electrons; oxygen; electrons; oxygen

Two Key Actions in Light Reaction: 1. ______ is split, yielding both _____ and ______. The ____ move through the light reactions. The ______ is what organisms such as ourselves breathe in.

water; initial electron acceptor

Two Key Actions in Light Reaction: 2. The electrons that are derived from the _____, and then given an energy boost by the sun's rays, are transferred to a different molecule: the _________.

ATP; power

The energetic fall of electrons through the electron transport chain between photosystems II and I also yields energy that produces ___, which is used to _____ the second stage of photosynthesis.

Calvin Cycle; RuBP

In ____carbon dioxide from the atmosphere (entering the plant thru the stomata) is brought together with a sugar, ___; this can be considered as a process of fixation, i.e. of a gas being incorporated into an organic molecule. The resulting compound is en

sugar G3P (food); sugar RuBP

The result of the Calvin cycle is the high-energy ___ _____, which is the product of photosynthesis. The low energy ____ ____ interacts with ATP and then receives energetic electrons from NADPH (that were originally from water that was boosted up the ener


can be used for energy or for plant growth; used to make proteins which then used as structural components of the plant or as enzymes; can be broken down into ATP to power plant's activities; Everything in the plant ultimately is derived from this in asso

stomata; stomata; sun's rays

In CAM photosynthesis these plants close their _____ during the day, to prevent water loss, and then open them at night. Under the cooler conditions of night, water vapor loss is minimized during passing in of carbon dioxide through the _____. Carbon diox

C3 or Calvin Cycle

This is used by a majority of plants and benefits are efficient use of ATP but the problem is photorespiration occurs

C4 Photosynthesis

This is used by plants in warm environments such as corn and sugarcane and benefits are less photorespiration but problem with it is it uses up more ATP

CAM Photosynthesis

This is used by plants in dry environments such as cactus and pineapples and benefit is less water loss but problems with it is that it uses up more ATP and is hard to "bank" enough CO?


The site of photosynthesis in a cell is the:
A. Mitochondrion
B. Central Vacuole
C. Stomata
D. Chloroplast


The products of photosynthesis are:
A. Oxygen and Sugar
B. Water and Sugar
C. CO? and Sugar
D. Oxygen and CO?


If you see a red leaf, what color(s) of light in the visible light spectrum is/are being reflected?
A. All colors except red
B. Red
C. All colors
D. No colors


Chlorophyll is found in which part of the plant cell?
A. Stroma
B. Cytoplasm
C. Thylakoid Membranes
D.Plasma Membrane


Chloroplasts transform _____ energy into the _____ energy of ATP.
A. Heat; Light
B. Light; Heat
C. Chemical; Light
D. Light; Chemical