BIO101: Introduction to Molecular and Cellular Biology, Topic: Unit 6: Photosynthesis | Saylor Academy (2023)

  • Unit 6: Photosynthesis

    Have you ever wondered how a plant grows from a tiny acorn into a giant oak tree? Where does all that biomass come from? How does it get the energy to grow? Photosynthesis is the fascinating process plants use to convert light energy to chemical energy. Because plants are at the bottom of the food pyramid in almost all ecological systems, understanding how they grow and develop will give you a greater understanding of your environment.

    Completing this unit should take you approximately 4 hours.

    • Upon successful completion of this unit,you will be able to:

      • explain the role of photosynthesis;
      • describe where matter originates and ends up during photosynthesis;
      • describe how photosynthesis converts low-energy molecules into energy-rich carbohydrates;
      • explain the role of the light-dependent phase of photosynthesis;
      • explain the role of the light-independent phase of photosynthesis, and describe how it is related to the light-dependent reactions;
      • explain how energy is transformed and transferred during photosynthesis;
      • explain how plants have adapted to deal with the problem of photorespiration;
      • identify the differences in photosynthesis in reference to CAM and C-4 plants; and
      • explain what the "carbon cycle" is and how it relates to the conservation of matter.
    • 6.1: Overview of Photosynthesis

      Photosynthesis is how green plants and other photosynthetic organisms use the power of sunlight to synthesize their own food from carbon dioxide and water. Photosynthesis harnesses sunlight by using green pigment chlorophyll and generates oxygen as a byproduct. The food and oxygen created by these autotrophs (organisms that make their own food) indirectly nourish and energize the whole earth.

      • Overview of Photosynthesis Page

        Read this overview of the process of photosynthesis. The text discusses basic photosynthetic structures and the two cycles in photosynthesis: the light and dark cycles, which we will explore later in the unit.

      • The Light-Dependent Reactions of Photosynthesis Page

        Read this review of the light-dependent reactions of photosynthesis. Light dependent reactions require light energy and water to create products ATM, NADPH, and oxygen.

        (Video) Photosynthesis: Crash Course Biology #8
      • The Calvin Cycle Page

        Read this review of the Calvin cycle, which is the light-independent reactions in photosynthesis. Light independent reactions require ATP, NADPH from the light reactions. and carbon dioxide to create sugar for the plant.

      • A Visual Explanation of Photosynthesis Page

        Watch this overview of photosynthesis, which gives a visual demonstration of how and where this process works inside the plant.

      • Light and Carbon Reactions Page

        Incorporating carbon from an inorganic source like carbon dioxide into organic compounds like glucose is called carbon fixation, and that is an extremely important function of photosynthesis. Carbon fixation results in products (organic compounds) that contain more chemical energy than the reactants (carbon dioxide molecules). Doing so requires an input of energy. The input of energy for the carbon fixation that occurs during photosynthesis is energy in the form of sunlight. Powered by that light energy, water molecules are split into oxygen and hydrogen atoms, and the hydrogen atoms from the water end up bonded to carbon atoms from carbon dioxide molecules to form high-energy carbohydrates. This occurs in two major pathways that comprise photosynthesis.

        Notice that the speaker explains why he also calls light-independent reactions"carbon reactions". The light reactions take energy from light and convert it into this chemical form of ATP and NADPH. They also produce oxygen. The carbon reactions are powered by the ATP and NADPH to do the work of photosynthesis.

        Watch these videos, which review the chemical processes that occur during the light-dependent and light-independent reactions of photosynthesis. Make sure you can describe how photosynthesis converts low-energy molecules into energy-rich carbohydrates. You should be able to explain how energy is transformed and transferred during photosynthesis.

        (Video) Biomolecules (Updated)
    • 6.2: Photosynthesis and Photorespiration

      The products of photosynthesis are sugars and oxygen. This anabolic process requires the reactants carbon dioxide and water. When there are significant amounts of these reactants, photosynthesis can nourish the plant and indirectly support life on earth. However, in environments where water and carbon dioxide are limited, there is a risk of photorespiration.

      • Photosynthesis Page

        Watch this video, which reviews the structures and cycles of photosynthesis. Pay attention to the chemical reactions that occur throughout the process, where they take place, and the products of these reactions. You should be familiar with the two stages of photosynthesis and the products of each stage of the process.

      • Light Reactions Page

        Watch this video about the details of the light reactions of photosynthesis. After you watch, you should be able to list the components of the chloroplasts, describe the role of chlorophyll in the light reactions, describe the photosystems and their role in the light reactions, and trace the movement of electrons in noncyclic electron flow.

      • Photophosphorylation Page

        (Video) Evolution of Photosynthesis: Were Anoxygenic or Oxygenic Phototrophs First? | GEO GIRL

        Watch this video about photophosphorylation of light reactions. After you watch, you should be able to describe the role of the cytochrome complex in the light reactions, trace the movement of electrons in cyclic vs. non-cyclic electron flow, and describe the role of ATP synthase in light reactions.

      • The Calvin Cycle Page

        Watch this video about the light-independent Calvin cycle. You should be able to describe the role of light-dependent byproducts ATP and NADPH in the Calvin cycle, illustrate and describe the function of each of the three phases of the Calvin cycle, and discuss the products of the Calvin Cycle.

      • Photorespiration Page

        Watch this lecture, which discusses an alternate mechanism of the Calvin cycle called photorespiration. You should be able to describe what happens when ribulose-bisphosphate carboxylase-oxygenase (RuBisCO) interacts with O2 instead of CO2 because of concentration differences.

    • 6.3: C-4 and CAM Photosynthesis

      A crucial step in the Calvin cycle is the fixation step, which takes in carbon dioxide and joins it with an intermediate compound (ribulose bisphosphate), thus incorporating inorganic carbon dioxide into an organic compound. The enzyme that catalyzes this step is called RuBisCO (ribulose bisphosphate carboxylase oxygenase). RuBisCO can operate to join either carbon dioxide or oxygen to ribulose bisphosphate. However, joining oxygen instead of carbon dioxide is counterproductive because no carbon fixation (the purpose of the Calvin cycle) takes place. This counterproductive process (incorporating oxygen instead of carbon dioxide) is called photorespiration.

      Two major categories of plant species have evolved ways around this problem:

      1. C-4 plants separate the process of carbon dioxide intake (which occurs in superficial cells called mesophyll cells) from the process of carbon fixation in the Calvin cycle (which occurs in deeper cells called bundle sheath cells).
      2. CAM plants take in carbon dioxide and store it in the form of organic acids during the night when their stomata are open. During the day, the organic acids get broken down to release the carbon dioxide for the Calvin cycle, while the stomata are closed (preventing oxygen from interfering).

      These two types of plants more efficiently operate the Calvin cycle because photorespiration is minimized.As you review C-4 plants and CAM plants, notice that they accomplish the same thing in two different ways. After you have read this section, you should be able to define the purpose of the stomata, describe the two photosynthetic adaptations that minimize photorespiration, and list the types of plants that have these adaptations.

      • C-4 and CAM Photosynthesis Page

        Watch these videos to learn about C-4 and CAM photosynthesis. Make sure you are able to explain the differences between these unique types of photosynthesis processes.

        (Video) 1. BIO 101 Introduction to Biology
    • 6.4: The Carbon Cycle

      The phrase carbon cyclerefers to the many chemical transformations that occur involving compounds containing carbon. The carbon cycle is cyclic because there is a continuous alternation between the carbon of organic compounds and the carbon of inorganic compounds. Inorganic carbon dioxide gets fixed (by autotrophs) into organic compounds. These organic compounds get converted into other organic compounds (including simple organic compounds like monosaccharides, nucleotides, and amino acids, as well as complex macromolecules like polysaccharides, nucleic acids, lipids, and polypeptides).

      The carbon in these organic compounds gets passed from organism to organism as they feed on each other. Some of the organic molecules get used as fuel by the organisms, and the oxidation of these organic fuels (to provide energy for the organisms) returns the carbon to inorganic form (carbon dioxide) to complete the cycle. In this cycle of transformations, carbon (matter) remains in the ecosystem (it is conserved). It is not destroyed; it is only transferred and transformed.

      • The Carbon Cycle Page

        Watch this video for an overview of the carbon cycle. Note that the carbon cycle has serious implications for the regulation of our atmosphere and climate, such as the production and accumulation of greenhouse gasses. We will not discuss this phenomenon in detail in this course, but it is an important aspect of the study of environmental science.

    • Unit 6 Assessment


What is bio101? ›

NOVA COLLEGE-WIDE COURSE CONTENT SUMMARY BIO 101 – GENERAL BIOLOGY I (4 CR.) Course Description. Focuses on biological processes with a chemical foundation, including macromolecules, cellular structure, metabolism, and genetics in an evolutionary context.

What will I learn in biology 101? ›

Students will investigate biological concepts including the chemical basis of life, cell structure and function, metabolism, reproduction, genetics, evolution, biological diversity and classification, plant structure and function, animal structure and function and ecology.

What do you study in molecular and cellular biology? ›

MOLECULAR AND CELLULAR BIOLOGY:- Molecular and cellular biology combines genetics and biochemistry to understand life at the molecular level and it aims to explain how molecular function produces the hierarchy of living cells, tissues and ultimately whole organisms.

Is cell a biology? ›

Cell biology is the study of cell structure and function, and it revolves around the concept that the cell is the fundamental unit of life. Focusing on the cell permits a detailed understanding of the tissues and organisms that cells compose.

How can I pass my biology exam? ›

Study Strategies for Biology
  1. Make learning a daily routine.
  2. Flesh out notes in 24-48 hour cycle. “ ...
  3. Study to understand, not just to memorize words.
  4. Learn individual concepts before integrating it together.
  5. Use active study methods.​
  6. You need to test yourself frequently to truly gauge how much you comprehend.

Is biology 1 hard in college? ›

Biology is one of the easier science subjects. Compared to physical sciences, those concerned with non-living things, it's less math-heavy and more straightforward. Conceptualizing biology facts is easier. Its principles are also easily observable for beginners.

How do I pass a college biology class? ›

Smart Study Strategies:
  1. Plan on two to three hours of study for each in-class hour.
  2. Read through the assigned text before each class and re-write notes from class time into your own words.
  3. Use flashcards with questions on one side and answers on the other for terms and phrases.
  4. Take advantage of mnemonics for complex ideas.
25 Sept 2017

What do I need to know before biology? ›

All biologists need to have some basic, foundational understanding of chemistry, physics, math, and statistics. But they don't have to become specialists in all these topics.

What are basics in biology? ›

The foundation of biology as it exists today is based on five basic principles. They are the cell theory, gene theory, evolution, homeostasis, and laws of thermodynamics.

Why is it important to study molecular and cellular biology? ›

As we have gained knowledge at this level, cell and molecular biology has become an indispensable prerequisite to understanding most biological problems. In medicine and health, the solutions to problems require intervention at the cell and molecular level.

Do you need physics for molecular biology? ›

All majors within the Department of Biological Sciences must also complete Corequisite Courses in Chemistry, Math, and Physics; these courses give you the scientific background to maximize your education within the Molecular Biology major.

Why do you want to study molecular biology? ›

The reason why research in molecular biology is so important is because the concepts discovered in this manner can be applied to mainstream biology, medicine, wildlife study and protection of endangered animals, food industry, pharmaceutical industry and environment protection.

What are the 4 types of cells? ›

The Four Main Types of Cells
  • Epithelial Cells. These cells are tightly attached to one another. ...
  • Nerve Cells. These cells are specialized for communication. ...
  • Muscle Cells. These cells are specialized for contraction. ...
  • Connective Tissue Cells.

What are the 7 functions of a cell? ›

Answer. Answer: movement, reproduction, response to external stimuli, nutrition, excretion, respiration and growth.

Who discovered cell? ›

Initially discovered by Robert Hooke in 1665, the cell has a rich and interesting history that has ultimately given way to many of today's scientific advancements.

What is the best time for study? ›

Most of the students prefer to study in the early morning, generally from 4 or 5 AM in the morning as the brain is more likely to concentrate. It could be the best option for students who have more stamina early in the day.

Is physics harder than biology? ›

Beginning university students in the sciences usually consider biology to be much easier than physics or chemistry. From their experience in high school, physics has math and formulae that must be understood to be applied correctly, but the study of biology relies mainly on memorization.

Is biology or chemistry easier? ›

Chemistry is more difficult than Biology because it requires critical thinking to solve complex problems. Chemistry is also more difficult than Biology because it requires more math and calculations to explain solutions to problems.

What is the hardest science? ›

Physics. Generally, physics is often deemed to be the hardest of all the sciences, especially as an A level qualification. Physics involves a lot of complex maths content – an aspect that most students struggle with.

How do I study biology last minute? ›

Last-minute Study Dos and Don'ts
  1. DON'T put life (completely) on hold. Yes – exam periods will be much more focussed on study than in general. ...
  2. DO make a plan. ...
  3. DON'T 'cram'. ...
  4. DO practice tests. ...
  5. DON'T over do it. ...
  6. DO get a good sleep. ...
  7. DON'T eat junk food. ...
  8. DO take breaks.

Why are biology exams so hard? ›

Biology and Biology majors are hard because of the vast amount of information required to learn but also involve a lot of unfamiliar concepts (some of which are difficult) and require mastering an unfamiliar vocabulary (which is true of any science).

How can I pass my exam with top grades? ›

8 simple tips for exam success
  1. Make the most of your study time.
  2. Don't just study solo.
  3. Deal with your stress.
  4. Ask for help.
  5. Get plenty of sleep.
  6. Prep the night before.
  7. Make the most of your morning.
  8. When you're in the exam room… take your time.

How can I study smart? ›

Studying 101: Study Smarter Not Harder
  1. Reading is not studying. Simply reading and re-reading texts or notes is not actively engaging in the material. ...
  2. Understand the Study Cycle. ...
  3. Spacing out is good. ...
  4. It's good to be intense. ...
  5. Silence isn't golden. ...
  6. Problems are your friend. ...
  7. Reconsider multitasking. ...
  8. Switch up your setting.

Do biologists need math? ›

Sometimes it's impossible or too difficult to answer a research question through traditional lab experiments, so biologists rely on math to develop models that represent the system they're studying, whether it's a metastasizing cancer cell or an emerging infectious disease.

Is biology easy? ›

Broadly speaking, biology is a comparatively simple science major to get into without a huge amount of training or expertise in the subject. One advantage students and professors will point out is that there is less complex mathematics to do in biology compared to your average science class in another subject.

Who is father of biology? ›

Therefore, Aristotle is called the Father of biology. He was a great Greek philosopher and polymath. His theory of biology also known as the “Aristotle's biology” describes five major biological processes, namely, metabolism, temperature regulation, inheritance, information processing and embryogenesis.

What is the function of cells? ›

They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body's hereditary material and can make copies of themselves. Cells have many parts, each with a different function.

Why is studying biology important? ›

As a field of science, biology helps us understand the living world and the ways its many species (including humans) function, evolve, and interact. Advances in medicine, agriculture, biotechnology, and many other areas of biology have brought improvements in the quality of life.

Is molecular biology hard? ›

It's not terribly hard, unless you're not truly interested in the material. As u/33554432 described, it is a LOT of transcription/translation detail to know. If you think those processes are cool, you'll be fine!

Is cell biology hard? ›

Cell bio is tough and it involves a lot of memorization, but it is straightforward information.

Is molecular biology a good course? ›

Molecular biology is a really exciting field to study and work in since it's constantly developing and changing to adapt to new research methodologies. This can be a very rewarding path for someone interested in sciences and research, but just be aware that it requires a lot of education and dedication.

What subjects are needed for molecular biology? ›

Molecular Biology is an interdisciplinary science that draws its major themes from biochemistry, cell biology, and genetics. Its emphasis is on the structure, chemistry, and functions of nucleic acids and focuses on the biochemical basis of cellular genetics.

Does molecular biology require chemistry? ›

Molecular biology, therefore requires a background in other disciplines such as chemistry, mathematics, physics and computer sciences. Principles from these disciplines underpin the new approaches made possible by biotechnology and genetic engineering.

What do you learn in molecular biology? ›

Molecular biology focuses on DNA, RNA and protein synthesis in cells and is closely related to the fields of cell biology, genetics, genomics, and biochemistry. Online courses are available in all of these areas of study from top universities and institutions including Harvard, MIT, and Rice.

What are the 5 biological techniques? ›

Most important techniques are Polymerase chain reaction (PCR), Expression cloning, Gel electrophoresis, Macromolecule blotting and probing, Arrays (DNA array and protein array).

Can a molecular biologist become a doctor? ›

Yes. Definitely. MD/PhD programs are a great choice for people who decide early that that they want to be physician–scientists and have built the necessary track record of academic success and research experience before they apply.

Which country is best for study molecular biology? ›

The United States is the best choice if you wish to study any degree in life science. Technological progress in molecular biology and biotechnology has increased specializations and new interdisciplinary fields.

What are 2 main types of cells? ›

There are two distinct types of cells: prokaryotic cells and eukaryotic cells.

What are the 3 shapes of cells? ›

The three principal shapes associated with epithelial cells are—squamous, cuboidal and columnar.

Why are there 2 types of cells? ›

There are only two main types of cells: prokaryotic and eukaryotic. Prokaryotic cells lack a nucleus and other membrane-bound organelles. Eukaryotic cells have a nucleus and other membrane-bound organelles. This allows these cells to have complex functions.

What is the smallest cell? ›

Mycoplasma or PPLO (Pleuropneumonia like organism) is the smallest cell.

What limits cell size? ›

What limits cell sizes and growth rates? Cell growth is limited by rates of protein synthesis, by the folding rates of its slowest proteins, and—for large cells—by the rates of its protein diffusion.

What are the 3 main functions of a cell? ›

Cells provide six main functions. They provide structure and support, facilitate growth through mitosis, allow passive and active transport, produce energy, create metabolic reactions and aid in reproduction.

Who is the father of dead cell? ›

Robert Hooke discovers dead cells using early microscope.

Who is the father of the cell? ›

The legacy of a founding father of modern cell biology: George Emil Palade (1912-2008)

What are the 3 principles of cell theory? ›

○ The Cell theory has three principles. 1) All organisms are made of cells. 2) All existing cells are produced by other living cells. 2) All existing cells are produced by other living cells.

What is taught in high school biology? ›

In biology, students study a variety of life processes and learn how different organisms meet the challenges of living in their environment. Students learn to use laboratory equipment and materials to collect data and then use a variety of data analysis skills to interpret the data.

What does biology 102 consist of? ›

BIOL 102 is the second portion of the Introductory Biology sequence and will cover the origins of life, biodiversity, whole organism biology of plants and animals, evolution and ecology.

What topics are covered in college biology? ›

These may include ecology and evolution, genetics, biostatistics, cell structure and function, biochemistry and molecular biology, human anatomy and physiology, and marine biology. Students are also required to take additional math and science courses, like biophysics and calculus.

How many topics are there in biology? ›

There are seven main subject areas covered in the exam, split across two separate papers: Cell biology. Organisation. Infection and response.

Why we study biology give 5 reasons? ›

  • Hands-on learning. ...
  • Discover the latest research methods. ...
  • Use the principles and apply them to anything. ...
  • Excellent career options. ...
  • Learn basic concepts of living. ...
  • Learn about the human body and how it thrives. ...
  • Explore food chains within ecosystems. ...
  • Understand the environment better.
15 Apr 2021

Is Khan Academy good? ›

Khan Academy is a reliable and highly useful source of academic learning. While it caters specifically to students in primary school through the college prep phase, anyone with a hunger to learn can benefit from Khan.

What is bio 2 taught? ›

Topics include evolution, biological diversity, plant structure and function, animal systems, and development and reproduction, and introductory concepts of ecology.

What are the topics in general biology 2? ›

  • Mendel's Laws of Inheritance.
  • Sex Linkage.
  • Central Dogma of Molecular Biology.
  • Recombinant DNA.
  • make a pedigree analysis in the learner's family using a simple genetic trait.
  • make a research paper/case study/poster on genetic diseases.

What does General biology 2 consist of? ›

This course provides an introduction to basic cell structure and function and the genetic basis of inheritance. Topics covered include: basic biochemistry, cell structure and function, metabolism and cellular respiration, genetics and molecular biology.

Is biology a hard major? ›

Biology is certainly a hard major but not quite as difficult as other STEM majors such as physics or chemistry. Most students find a biology degree difficult to pursue because it has an extensive syllabus, lots of lab work, several challenging concepts, unfamiliar vocabulary, and lots of things to memorize.

What is the best topic for biology project? ›

This list ends with several other fascinating research proposal topics, such as:
  • Molecular and Genome Evolution.
  • Comparative Genomics.
  • The Evolutionary Biology of Infectious Diseases.
  • Modern Technology and Scientific Tools in Biology.
  • Neurobiological Explanation of Sleep.
  • Symbiosis in Parasites.
  • Metabolism & Physical Exercise.

What are the 5 major biological concepts? ›

The five central themes of biology are structure and function of cells, interactions between organisms, homeostasis, reproduction and genetics, and evolution.

What do year 12 learn in biology? ›

In Year 12 Biology you will build on the concepts you learned in Year 11, expanding your understanding to cover genetics and how we use biotechnology to manipulate biological systems for our own benefit. The syllabus covers the application of biotechnology to agriculture, industry and medicine.

What are the 4 types of biology? ›

There are four primary categories: botany, human biology, microbiology and zoology.

What do year 11 learn in biology? ›

During year 11 you will learn about the structure and function of organisms as well as develop an understanding of the Earth's biodiversity and the effect of evolution. You will need to be able to develop hypotheses, as well as design and evaluate experiments.


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