Download the App!

Get 24/7 study help with the Numerade app for iOS and Android! Enter your email for an invite.

Sent to:
Search glass icon
  • Login
  • Textbooks
  • Ask our Educators
  • Study Tools
    Study Groups Bootcamps Quizzes AI Tutor iOS Student App Android Student App StudyParty
  • For Educators
    Become an educator Educator app for iPad Our educators
  • For Schools

Photosynthesis

Photosynthesis is a process used by green plants, algae, and cyanobacteria to convert light energy into chemical energy that can later be used to create the building blocks of organic compounds using carbon dioxide, water, and minerals from the soil. This process was first discovered and described by Robert Hooke in 1666. Photosynthesis occurs in plants, algae, and cyanobacteria. It is also a key process in the oxygen cycle. Photosynthesis is conducted during the day or night, in a process called "phototropism", which is the technical term for plant movement toward or away from light. Water is a solvent for many organic compounds, and the chemical energy of their bonds is released in the form of a very dilute acid. Most often, the photochemical reaction is carried out in the thylakoid membranes of the chloroplasts, although some organisms have specialized stromata or plastids to conduct the splitting of water. Photosynthesis provides the energy in the form of reducing power to drive the chemical reactions that form carbohydrates from atmospheric carbon dioxide and water. Photosynthesis is vital for all life on Earth. In the first stage, light-dependent reactions use light energy to generate a reduced and oxidized state of water (H 2O) from which the energy is released to make the three types of carbohydrates that can be used as carbon-containing compounds: sugars (such as glucose), starches (such as amylose), and cellulose. These carbohydrates are used as a source of energy and carbon compounds for cellular respiration. In plants, the carbohydrates generated in this way are stored in the form of various polysaccharides. The second stage of photosynthesis uses the energy of photophosphorylation to split water into its components of hydrogen and oxygen. The hydrogen is used as the raw material for the third stage of photosynthesis, which uses the energy from water splitting to make sugars and other organic compounds. During this stage, carbon dioxide and water are used as sources of carbon and oxygen, respectively. In the third stage, the light-independent reactions continue to use the energy from water splitting to oxidize the remaining NADP+ (nicotinamide adenine dinucleotide phosphate) to NADPH (nicotinamide adenine dinucleotide phosphate). This is used to oxidize carbon dioxide and water to form two molecules of sugar and release oxygen as a waste product. The sugar is then used as a raw material to make other organic compounds, such as cellulose and starch, which are stored in the form of polysaccharides.

Overview

47 Practice Problems
View More
01:55
Biology: Concepts and Investigations

Define these terms and arrange them from smallest to largest: thylakoid membrane; photosystem; chloroplast; granum; reaction center

Photosynthesis
Alexander Cheng
02:00
What Is Life? A Guide to Biology

During the Krebs cycle:
a) the products of glycolysis are further broken down, generating additional ATP and the high-energy electron carrier NADH.
b) high-energy electron carriers pass their energy to molecules of sugar, which store them as potential energy.
c) the products of glycolysis are further broken down, generating additional ATP and ethanol.
d) cellular respiration can continue even in the absence of oxygen.
e) the products of glycolysis are converted to acetyl-CoA.

Energy
Dennis Howard
00:48
Biology Concepts and Applications

Closed stomata ___
a. limit gas exchange
b. permit water loss
c. prevent photosynthesis
d. absorb light

Where It Start—Photosynthesis
Aditya Sood

The Light Reactions

51 Practice Problems
View More
00:11
Biochemistry

What would be the effect on plants if photorespiration did not exist?

Photosynthesis
Sam Limsuwannarot
02:47
Biology: Concepts and Investigations

In some ways, chlorophyll can be thought of as a solar panel like the ones used to generate electricity at power plants. Using terms such as granum, photosystem, ATP, and chlorophyll, explain this comparison.

Photosynthesis
Alexander Cheng
00:48
Biology: The Essentials

In 1941 , biologists exposed photosynthesizing cells to water containing a heavy oxygen isotope, designated $^{18}$ O. The "labeled" isotope appeared in the $\mathrm{O}_{2}$ gas released in photosynthesis, showing that the oxygen came from the water. Where would the 180 have ended up if the researchers had used $^{18} \mathrm{O}$ -labeled $\mathrm{CO}_{2}$, instead of $\mathrm{H}_{2} \mathrm{O} ?$

Photosynthesis
Kevin Barayuga

Electron Flow

52 Practice Problems
View More
00:21
Essential Cell Biology

In the following statement, choose the correct one of the alternatives in italics and justify your answers. "If no $\mathrm{O}_{2}$ is available, all components of the mitochondrial electrontransport chain will accumulate in their reduced/oxidized form. If $\mathrm{O}_{2}$ is suddenly added again, the electron carriers in cytochrome $c$ oxidase will become reduced/oxidized before/after those in NADH dehydrogenase."

Energy Generation in Mitochondria and Chloroplasts
00:27
Biochemistry

What are the principal metal ions used in electron transfer in chloroplasts? Compare them to the ions found in mitochondria.

Photosynthesis
Sam Limsuwannarot
01:52
Biochemistry

Are electron transport and oxidative phosphorylation the same process? Why or why not?

Electron Transport and Oxidative Phosphorylation
Sydney Atkins

The Calvin Cycle

38 Practice Problems
View More
01:49
Biology: Concepts and Investigations

Explain why each of the following misconceptions about photosynthesis is false:
a. Only plants are autotrophs.
b. Plants do not need cellular respiration because they carry out photosynthesis.
c. Chlorophyll is the only plant pigment.

Photosynthesis
Nicholas L'Heureux
00:46
Biology Concepts and Applications

The Calvin-Benson cycle starts with ___
a. the absorption of photon energy
b. carbon fixation
c. the release of electrons from photosystem II
d. NADP+ formation

Where It Start—Photosynthesis
Aditya Sood
00:57
Biology: The Unity and Diversity of Life

Light-independent reactions in plants proceed in/at the ____________ of chloroplasts.
a. thylakoid membrane
c. stroma
b. plasma membrane
d. cytoplasm

Where It Starts—Photosynthesis
Aditya Sood

Photorespiration

7 Practice Problems
View More
01:16
Biology: Concepts and Investigations

How does photorespiration counteract photosynthesis?

Photosynthesis
Sulav Pokhrel
00:40
Cracking the AP Biology Exam

Directions: Each group of questions consists of five lettered headings followed by a list of numbered phrases or sentences. For each numbered phrase or sentence, select the one heading that is most closely related to it and fill in the corresponding oval on the answer sheet. Each heading may be used once, more than once, or not at all in each group.
Questions $6-9$
(A) Stroma
(B) Thylakoids
(C) Photolysis
(D) Carotenoids
(E) Ribulose bisphosphate
Contains enzymes of photophosphorylation

Photosynthesis
Joanna Quigley
01:05
Cracking the AP Biology Exam

Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case. Answers can be found here.
All of the following statements are correct regarding the light reaction in photosynthesis EXCEPT
(A) The antennae pigments capture sunlight.
(B) The reaction center in photosystem II is P680.
(C) Light energy is converted to chemical energy.
(D) The electrons are activated and passed along an electron transport chain.
(E) Carbon dioxide is used to make glucose.

Photosynthesis
Joanna Quigley

Alternative Photosynthesis Pathways

13 Practice Problems
View More
00:58
Introduction to General, Organic and Biochemistry

(Chemical Connections 29 A) Photosystems I and II are complex factories of proteins, chlorophyll, and many cofactors. Where are these photosystems located in plants, and in which reaction of photosynthesis do they participate?

Biosynthetic Pathways
Emily Himsel
02:52
Biology: Concepts and Investigations

Photosynthesis takes place in plants, algae, and some microbes. How does it affect a meat-eating animal?

Photosynthesis
Sulav Pokhrel
01:17
Biology: The Essentials

Define these terms and arrange them from smallest to largest: thylakoid membrane; photosystem; chloroplast; granum; reaction center.

Photosynthesis
Kevin Barayuga

Mitochondria vs Chloroplasts

22 Practice Problems
View More
00:33
Biochemistry

Uncouplers of oxidative phosphorylation in mitochondria also uncouple photoelectron transport and ATP synthesis in chloroplasts. Give an explanation for this observation.

Photosynthesis
Sam Limsuwannarot
13:47
Essential Cell Biology

In an insightful experiment performed in the 1960 s, chloroplasts were first soaked in an acidic solution at $\mathrm{pH} 4$ so that the stroma and thylakoid space became acidified (Figure $Q 14-17$ ). They were then transferred to a basic solution $(\mathrm{pH} 8)$. This quickly increased the $\mathrm{pH}$ of the stroma to $8,$ while the thylakoid space temporarily remained at $\mathrm{pH} 4 .$ A burst of ATP synthesis was observed, and the pH difference between the thylakoid and the stroma then disappeared.
A. Explain why these conditions lead to ATP synthesis.
B. Is light needed for the experiment to work?
C. What would happen if the solutions were switched so that the first incubation is in the pH 8 solution and the second one in the pH 4 solution?
D. Does the experiment support or question the chemiosmotic model?
Explain your answers.

Energy Generation in Mitochondria and Chloroplasts
Nicole Hewett
06:55
Essential Cell Biology

A. How do cells in plant roots survive, since they contain no chloroplasts and are not exposed to light?
B. Unlike mitochondria, chloroplasts do not have a transporter that allows them to export ATP to the cytosol. How, then, do plant cells obtain the ATP that they need to carry out energyrequiring metabolic reactions in the cytosol?

Energy Generation in Mitochondria and Chloroplasts
Nicole Hewett

Life's Dependency on Photosynthesis

30 Practice Problems
View More
01:55
What Is Life? A Guide to Biology

During photosynthesis, which step is most responsible for a plant's acquisition of new organic material?
a) the "building" of NADPH during the Calvin cycle
b) the excitation of chlorophyll molecules by photons of light
c) the "plucking" of carbon atoms from the air and fixing of them to organic molecules within the chloroplast
d) the loss of water through evaporation
e) the production of ATP during the light reactions

Energy
Dennis Howard
00:46
Biology: The Unity and Diversity of Life

Plants use ______________ as an energy source to drive photosynthesis.
a. sunlight
c. $\mathrm{O}_{2}$
b. hydrogen ions
$\mathrm{d} . \mathrm{CO}_{2}$

Where It Starts—Photosynthesis
Aditya Sood
00:51
Biology: The Unity and Diversity of Life

What substance is not part of the Calvin-Benson cycle?.
a. ATP
b. NADPH
c. RuBP
d. PGAL
e. $\mathrm{O}_{2}$
f. $\mathrm{CO}_{2}$

Where It Starts-Photosynthesis
Brenda Sanchez

Get 24/7 study help with our app

 

Available on iOS and Android

About
  • Our Story
  • Careers
  • Our Educators
  • Numerade Blog
Browse
  • Bootcamps
  • Books
  • Notes & Exams NEW
  • Topics
  • Test Prep
  • Ask Directory
  • Online Tutors
  • Tutors Near Me
Support
  • Help
  • Privacy Policy
  • Terms of Service
Get started