Week 7 — Readings & Resources · Photosynthesis

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective covered: Objective 4 — Explain photosynthesis as an ordered, two-stage process (light reactions → Calvin cycle) that stores light energy in sugar.

How to use this page

Everything here is a link to an external resource — open it in your browser, the same way you'd open a YouTube link. Nothing needs to be downloaded.

This week's load is deliberately light: 2 short videos + 2 short readings, grouped by the ideas from the lecture, plus one optional free online reference. Watch or read one item per group and you're ready for the quiz; do all of them and you'll be very comfortable. Total time is roughly 35–45 minutes if you do everything, far less if you pick one per group.

Order that matches the lecture: ① the big picture + equation → ② the light-dependent reactions (and where O₂ comes from) → ③ the Calvin cycle → ④ photosynthesis vs. respiration & the big picture.

A habit to start now: before you trust any biology claim — in these resources or anywhere — ask the questions from class: Which stage comes first, and where? What goes in and what comes out? And where does the oxygen actually come from?

① The Big Picture & the Equation

Maps to Lecture Segments 2–3. Photosynthesis captures light energy and stores it in sugar; the equation is CO₂ + H₂O + light → glucose + O₂, and it all happens inside the chloroplast (thylakoid + stroma).

Video — "Photosynthesis (UPDATED)" (Amoeba Sisters)
🔗 https://www.youtube.com/watch?v=CMiPYHNNg28
Why it earns the click: a friendly ~7-minute tour of the exact two-stage story we built on the board — the equation, chlorophyll and pigments, the light-dependent reactions, and the Calvin cycle — and it compares photosynthesis to last week's respiration equation. (Use the chapter markers: light reactions at 3:33, Calvin cycle at 4:36.)
⏱ ~7 min

Reading — "Overview of Photosynthesis" (OpenStax Biology 2e, §8.1)
🔗 https://openstax.org/books/biology-2e/pages/8-1-overview-of-photosynthesis
Why it's assigned: the cleanest plain-language version of what photosynthesis does, the equation, and the chloroplast structures we labeled in class (thylakoid, stroma, granum) — free to read online, no account needed. Read down to "The Two Parts of Photosynthesis."
⏱ ~10 min

② The Light-Dependent Reactions — and Where the Oxygen Comes From

Maps to Lecture Segment 4. In the thylakoid membrane, chlorophyll absorbs light, water is split (releasing the O₂ you breathe), and the energy is captured as ATP and NADPH.

Reading — "The Light-Dependent Reactions of Photosynthesis" (OpenStax Biology 2e, §8.2)
🔗 https://openstax.org/books/biology-2e/pages/8-2-the-light-dependent-reactions-of-photosynthesis
Why it's assigned: shows how pigments absorb light and — the key fact for the quiz — that water is split to replace electrons, which is the source of the released oxygen. You don't need the photosystem-I/II details; focus on inputs (light, water) and outputs (O₂, ATP, NADPH).
⏱ ~10 min

③ The Calvin Cycle (Light-Independent Reactions)

Maps to Lecture Segment 5. In the stroma, the ATP and NADPH from Stage 1 are spent to fix CO₂ into sugar (G3P → glucose) — this stage doesn't use light directly, but it stops without the light reactions' products.

Reading — "Using Light Energy to Make Organic Molecules" (OpenStax Biology 2e, §8.3)
🔗 https://openstax.org/books/biology-2e/pages/8-3-using-light-energy-to-make-organic-molecules
Why it's assigned: walks through the Calvin cycle — carbon fixation, reduction using ATP/NADPH, and the build-up of sugar — and explains why "light-independent" does not mean "works in the dark." The "Energy Flow" section ties photosynthesis to respiration.
⏱ ~10 min

④ Photosynthesis vs. Respiration & the Big Picture

Maps to Lecture Segment 7. The line to carry out of this week: photosynthesis and respiration are roughly reverse processes, the by-products of one are the inputs of the other, and plants do both.

Video — "Photosynthesis: Crash Course Biology #8" (CrashCourse)
🔗 https://www.youtube.com/watch?v=sQK3Yr4Sc_k
Why it earns the click: a fast, energetic walk through the inputs, the chloroplast, the light reactions (water split, ATP synthase), and the three phases of the Calvin cycle — a good second pass after the Amoeba Sisters overview, with chapter markers if you want to jump to the dark reactions at 7:55.
⏱ ~13 min

Optional one-stop references (free online)

• Khan Academy — Photosynthesis in plants. A free unit with short articles and videos on the chloroplast, the light reactions, and the Calvin cycle. A good place to return to all term.
  🔗 https://www.khanacademy.org/science/biology/photosynthesis-in-plants
• Khan Academy — "Intro to photosynthesis" (article). A concise written overview of the equation, the two stages, and where each happens — handy for a quick pre-quiz skim.
  🔗 https://www.khanacademy.org/science/biology/photosynthesis-in-plants/introduction-to-stages-of-photosynthesis/a/intro-to-photosynthesis

Pick-one quick path (≈17 min total)

In a hurry? Do exactly these two and you'll be ready for the quiz:
1. Watch "Photosynthesis (UPDATED)" (groups ①–③ in one video).
2. Skim "Overview of Photosynthesis" (group ①) and the first half of "Using Light Energy to Make Organic Molecules" (group ③) for the Calvin cycle.

Heads-up (links rot): these point to outside sites that occasionally move or rename pages. If a link ever fails, tell Prof. Castellano and use the OpenStax or Khan Academy references above in the meantime.