Biology Photosynthesis Overview

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Questions and Answers

How do phytochromes influence germination in plants?

They switch between active and inactive forms based on light conditions. (correct)

They absorb ultraviolet light to enhance growth.

They convert stored energy into sugars for the plant.

They directly stimulate root growth during photosynthesis.

What is the effect of far-red light on seed germination?

It increases the time seeds remain dormant. (correct)

It inhibits germination and encourages upward growth. (correct)

It enhances the absorption of nutrients from the soil.

It promotes immediate germination regardless of conditions.

Which factor primarily determines the flowering time of a plant?

The amount of sunlight received.

The temperature of the environment.

The type of nutrients available in the soil.

The duration of the night period. (correct)

In which scenario would a plant be less likely to germinate?

When it receives prolonged far-red light. Signup and view all the answers

What seasonal behavior is exhibited by some plants like spring ephemerals?

They break dormancy as seasons begin in their ideal growing conditions. Signup and view all the answers

Which of the following is true about the active (Pfr) and inactive (Pr) forms of phytochromes?

Pfr induces processes like germination. Signup and view all the answers

How can a strong burst of red light disrupt a plant's flowering pattern?

By activating phytochromes to promote flowering. Signup and view all the answers

What role does phototropism play in plant behavior?

It helps plants grow towards sunlight for photosynthesis. Signup and view all the answers

What primarily drives the upward movement of water through the plant's xylem?

Cohesion and adhesion of water molecules Signup and view all the answers

What role do root hairs play in water movement within plants?

Increase surface area for water absorption Signup and view all the answers

What is the main consequence of transpiration in plants?

Decreased water potential in the xylem Signup and view all the answers

What is the sequence of water movement from soil to xylem?

Soil → Root hairs → Epidermis → Cortex → Xylem Signup and view all the answers

In which part of the plant does guttation primarily occur?

Leaf margins due to root pressure Signup and view all the answers

What effect does transpiration have on the water potential gradient in a plant?

It creates a negative pressure that pulls water up Signup and view all the answers

How is sugar transported from the source to the sink in plants?

Via diffusion into the phloem and subsequent movement Signup and view all the answers

What is the role of proton pumps in the translocation of phloem sap?

To drive sugar movement into phloem cells Signup and view all the answers

What is the primary location of the light-dependent reactions in photosynthesis?

Thylakoids Signup and view all the answers

What is a key outcome of the light-independent reactions, also known as the Calvin Cycle?

Formation of glucose Signup and view all the answers

Which structure within the chloroplast is involved in the formation of a proton gradient during photosynthesis?

Lumen Signup and view all the answers

What role does rubisco play in the Calvin Cycle?

Fixes carbon dioxide Signup and view all the answers

How does transpiration primarily benefit plants?

Regulates temperature and nutrient flow Signup and view all the answers

Which of the following factors does NOT affect the rate of transpiration in plants?

Soil pH Signup and view all the answers

What is the impact of photoperiod on plant growth?

It influences flowering and seed production. Signup and view all the answers

What is transported through the plant's phloem?

Photosynthetic products like sugars Signup and view all the answers

Study Notes

Today's Tasks

Discuss productivity activity
Photosynthesis diagram
Homework: HW #3, HW quizzes 1 & 2 due day 2

Photosynthesis Diagram

Draw a detailed diagram of all the reactions in photosynthesis.
Use a piece of green paper.
Follow instructions from the next slide.
Due on test day.

Chloroplast Structure

Cytoplasm
Outer membrane
Inner membrane
Thylakoids
Grana
Stroma
Lumen
Light reactions
Location
Inputs/reactants: Source of e-, Source of H+
Photosystem I and II
Path of electrons
Electron transport chains
H+ gradient
NADPH formation
ATP synthase
Outputs/products: Source of O₂ waste

Cyclic electron flow

Where?
When?
Why?

Light-Independent Reactions (Calvin Cycle)

Location
Inputs/reactants: Energy carriers, Carbons
Starting compound
Rubisco and carbon fixation
Regeneration of starting product
Outputs/products

ET50

The effective time it takes for 50% of leaves to float.
Data in graph (refer to image).

Transpiration Lab

Conduct the transpiration lab.
Complete the worksheet.
Pay attention to water potential.
Due date: Day 3

Homework quiz #3

Due date; Day 3

Productivity Activity

Collect the activity materials.
Due date: Day 3

EQ 4.4a: Transpiration

Activities: Transpiration interactive, Transpiration lab (dry lab)

EQ 4.4b: Signaling

Activities: Plant cell signaling
Tasks: Finish Photosynthesis diagram, Collect Productivity Activity

Plant Cell Signaling

EQ: How do plants respond to conditions in their environment?
Plant behaviors accomplished through chemical signaling.

Photoperiodism

Seasonal behaviors
Some plants flower in winter, some in summer.
Some flower independent of light conditions.
Day length requirements for flowering in three categories of plants: Short day plant, Long day plant, Natural day plant

Tropisms

Phototropism
Gravitropism
Thigmotropism

Germination

Plant seeds break dormancy and sprout at the beginning of their ideal growing season.
Phytochromes are light-absorbing pigments that respond to light and influence a plant's behavior.
Red light = increases germination, branching and is abundant in direct sunlight
Far-red light = inhibits germination, increases upward growth.

Phytochromes

Photo-reversible, alternating between active (Pfr) and inactive (Pr) form.
Pfr induces germination. Red light is absorbed by mature plants who are in a good spot to grow.
Seeds in shade receive more far-red light, which inhibits growth, so seed stays dormant.

Water Potential (Ψw)

High in xylem, low in the air.
Water moves from high to low.

Transpirational Pull

Water vapor evaporation from leaves pulls water up the xylem through cohesion and adhesion.
Due to differences in Ψw between xylem, leaf spaces, and the air..

Root Pressure

Root hairs increase surface area (mycorrhizae).
Selective transport of minerals occurs, then water follows via osmosis.
No energy needed to move water.
Leads to guttation.

Translocation of Phloem Sap

Source to sink.
Sugar moves from source cells into phloem cells (sieve-tube members), driven by proton pumps.

Water Cycle (Diagram)

Shows the different stages and processes involved in the water cycle..

Homework:

Enjoy your break!
Test on day 2.

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Description

Explore the intricate details of photosynthesis, including the structure of chloroplasts and the various reactions involved. This quiz will test your understanding of both light-dependent and light-independent reactions, as well as the electron transport chain and cyclic electron flow. Prepare to enhance your knowledge of this essential biological process.