Unit 4 - Photosynthesis Flashcards
Because they cannot make their own food, __________________ rely on the food making ability of green plants.
heterotrophs
Why is it accurate to say that heterotrophs rely indirectly on the sun for their energy?
Heterotrophs rely indirectly on the sun for their energy because the energy stored in the organic compounds they consume originally came from the sun, captured through photosynthesis by autotrophs.
Organisms that make their own food are called ________________ and therefore are the ________________ for the biosphere.
autotrophs, producers
Which of the following is not an autotroph
a. Some bacteria that photosynthesize
b. Algae
c. Tree
d. Mushroom
Mushroom
Mushrooms are heterotrophs that obtain their nutrients by decomposing organic matter or by parasitizing other organisms. They are not capable of producing their own food through photosynthesis.
Why is it important for organisms to acquire organic compounds?
It’s important for organisms to acquire organic compounds because they contain the necessary carbon and energy sources for growth, maintenance, and energy production within an organism.
Do both plants and animals perform cell respiration?
Yes, both plants and animals perform cell respiration. Cell respiration is the process by which cells break down organic molecules to produce ATP, the energy currency of the cell, for various cellular functions.
Do both plants and animals photosynthesize?
No, only plants perform photosynthesis. Animals **do not possess the necessary cellular structures **(like chloroplasts) or pigments (like chlorophyll) required to carry out photosynthesis. Instead, animals acquire energy by consuming organic matter, either plant-based or from other animals.
Where in the chloroplast does the light dependent reaction occur?
The light-dependent reactions occur in the thylakoid membranes of the chloroplast.
Where in the chloroplast does the light independent reaction occur?
The light-independent reaction occur in the stroma of the chloroplast.
The part of the leaf where most photosynthesis occurs is the:
a. Vein
b. Stomata
c. Mesophyll
d. Cuticle
c. Mesophyll
What role do the stomata play in photosynthesis?
Stomata play a crucial role in photosynthesis by regulating gas exchange. They open to allow the entry of carbon dioxide (CO2) needed for photosynthesis and the exit of oxygen produced during the process. They also control water vapor loss from the leaf.
What is the stroma
The stroma is the fluid-filled space inside the chloroplast, surrounding the thylakoid membranes.
What is the Thylakoid?
Thylakoids are membrane-bound compartments within chloroplasts. The light-dependent reaction occurs in the thylakoid. It contains chlorophyll and other pigments that absorb sunlight.
Why is the chloroplast compartmentalized by 3 membranes?
Chloroplasts are compartmentalized by three membranes to create distinct spaces for different stages of photosynthesis and to optimize efficiency. This compartmentalization helps separate processes like the movement of electrons during the light reactions in the thylakoid membrane and the Calvin cycle in the stroma.
What are the two major functions of veins (Xylem & phloem)?
Xylem transports water and minerals from the roots to the rest of the plant. Phloem transports the sugars produced during photosynthesis from the leaves to other parts of the plant.
Parts of the leaf and their function
Cuticle: A waxy layer on the leaf’s surface, reducing water loss.
Epidermis: The outer layer of cells protecting the leaf.
Mesophyll: The middle layer containing chloroplasts where photosynthesis occurs
Stomata: Holes on the leaf surface regulating gas exchange.
Veins (Xylem & Phloem): Transport systems for water, minerals, and sugars.
Parts of chloroplasts and their functions.
Thylakoid: Membrane-bound compartments where the light-dependent reactions occur.
Granum (plural: Grana): Stack of thylakoids.
Stroma: Fluid-filled space surrounding the thylakoids, where the Calvin cycle (light-independent reactions) occurs.
Inner membrane: Encloses the stroma.
Outer membrane: Encloses the entire chloroplast.
What are the two sets of reactions in photosynthesis called?
The two sets of reactions in photosynthesis are the light-dependent reactions (occurring in the thylakoid membranes) and the light-independent reactions or the Calvin cycle (taking place in the stroma).
What are the reactants and products of light dependent reaction?
Reactants: Water (H2O), ADP, NADP+
Products: Oxygen (O2), ATP, NADPH
Summarize what happens in light reaction
Light energy is absorbed by chlorophyll and other pigments in the thylakoid membranes. Water molecules are split (photolysis), releasing oxygen, protons (H+), and electrons. These electrons move through the electron transport chain, creating a proton gradient that drives ATP synthesis and reducing NADP+ to NADPH. Oxygen is released as a byproduct.
What are the reactants and products of light independent reaction?
Reactants: ATP, NADPH, CO2
Products: Glucose (C6H12O6), ADP, NADP+
Summarize what happens in the light independent reaction? (Calvin Cycle)
Carbon dioxide combines with a five-carbon molecule to make a six-carbon compound using an enzyme called Rubisco. This compound goes through a series of steps using energy from light to produce sugars like glucose. In the process, some molecules like** ATP** and NADPH are **used and recycled **to keep the cycle going.
Write the overall balanced equation for photosynthesis.
6CO2 + 6H2O → C6H12O6 + 6O2
Why is carbon dioxide essential in the process of photosynthesis?
Carbon dioxide (CO2) is essential in photosynthesis because it provides the carbon source for glucose and other organic molecules synthesized during the light-independent reactions (Calvin cycle). Through a series of enzyme-driven reactions, CO2 is fixed and converted into organic compounds, utilizing the energy from ATP and NADPH produced in the light-dependent reactions. This process is crucial to produce carbohydrates and the overall synthesis of organic molecules by plants.
