Cellular Respiration: Detailed Anatomy & Photosynthesis Nuance

Detailed Concepts Part 1

What is the function of the Cuticle?

A waxy layer on the top of the leaf that prevents water loss.

What is the function of the Upper Epidermis?

A clear cell layer that protects the leaf but allows light to pass through to the photosynthetic cells below.

What is the Palisade Mesophyll?

The layer of tightly packed, column-shaped cells just under the epidermis where MOST photosynthesis occurs (lots of chloroplasts).

What is the Spongy Mesophyll?

The layer of loosely packed cells with air spaces to allow for gas exchange (CO2 and Oxygen) within the leaf.

What is Xylem?

Vascular tissue in the stem/veins that transports WATER up from the roots.

What is Phloem?

Vascular tissue in the stem/veins that transports FOOD (Sugars) down from the leaves to the rest of the plant.

What is a Thylakoid?

A single, pancake-like disc inside the chloroplast where the Light Dependent Reactions occur.

What is a Granum (plural: Grana)?

A stack of thylakoids inside the chloroplast.

What is the Stroma?

The fluid-filled space surrounding the grana inside the chloroplast; where the Calvin Cycle (Light Independent Reactions) occurs.

What specifically happens to Water molecules during the Light Dependent Reactions?

They are split (Photolysis) to release Electrons (for energy), Hydrogen ions, and Oxygen (waste).

What happens to the rate of photosynthesis as Light Intensity increases?

The rate increases up to a certain point, then plateaus (levels off) because the light-absorbing pigments are saturated.

What happens to the rate of photosynthesis as Temperature increases?

The rate increases initially, but if it gets too hot, the rate drops to zero because the enzymes denature (break down).

What specific range of light wavelengths do plants absorb best?

Blue-violet (400-500 nm) and Red-orange (600-700 nm) light.

Which color of light is LEAST effective for photosynthesis?

Green light (because it is reflected, not absorbed).

What is the difference between ATP and Glucose in terms of energy storage?

ATP is for short-term, immediate energy usage; Glucose is for long-term, stable energy storage and transport.

What are Carotenoids?

Accessory pigments (orange/yellow) that absorb light in wavelengths that chlorophyll cannot, broadening the range of light a plant can use.