Biology Chapter on Cell Theory and Microscopy

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Questions and Answers

What is the primary role of auxins in plant movement?

To regulate cell elongation. (correct)

To initiate root growth.

To increase the production of chlorophyll.

To reduce water loss.

In what way do auxins affect root growth in response to gravity?

They stimulate equal growth on both sides.

They redistribute to the lower side promoting downward growth. (correct)

They cause the roots to bend upwards.

They inhibit growth on the upper side.

What is gravitropism?

Growth response to temperature changes.

Directional growth response to gravity. (correct)

Plant growth response to moisture.

Plant movement towards nutrients.

How do plants primarily maximize their exposure to sunlight?

By bending towards light sources. Signup and view all the answers

What triggers the accumulation of auxins on one side of a plant?

Differential light exposure. Signup and view all the answers

What occurs in a hypertonic solution?

Water moves out of the cell, leading to cell shrinking. Signup and view all the answers

What is primary active transport?

Use of ATP to move molecules against their concentration gradient. Signup and view all the answers

What characterizes a hypotonic solution?

Water enters the cell, potentially causing it to burst. Signup and view all the answers

What is the function of the sodium-potassium pump?

Maintains ion concentrations across the cell membrane. Signup and view all the answers

Which of the following best describes bulk transport?

Movement of substances through vesicles. Signup and view all the answers

In what kind of transport does symport occur?

Both molecules move in the same direction. Signup and view all the answers

Which term describes a membrane that allows certain particles to pass while excluding others?

Semi-permeable membrane. Signup and view all the answers

What process describes the uptake of solid particles into the cell?

Phagocytosis. Signup and view all the answers

What advancement in technology allowed for the detailed observation of cellular organelles, thus supporting modern cell theory?

Electron microscopes Signup and view all the answers

In an experiment, which variable is manipulated to observe its effects on the responding variable?

Independent variable Signup and view all the answers

What is one major disadvantage of using a compound light microscope?

It has a very limited magnification Signup and view all the answers

Which type of microscope is ideal for observing pale objects against a dark background?

Dark field microscope Signup and view all the answers

Which type of microscope is designed to examine live organisms without causing damage?

Phase microscope Signup and view all the answers

What advantage do fluorescent microscopes provide during observation?

They can identify pathogens and visualize proteins Signup and view all the answers

Which component of an experiment includes all factors kept constant to ensure results are due to the manipulated variable?

Controlled variables Signup and view all the answers

What is a notable feature of bright field microscopes compared to other types?

They create images against a bright background Signup and view all the answers

What is a fundamental characteristic of particles in a solid state?

Particles are tightly packed and only vibrate in place. Signup and view all the answers

Which statement correctly describes a concentration gradient?

It highlights the difference in solute concentration between two areas. Signup and view all the answers

How do temperature changes affect particle movement?

Higher temperatures increase the kinetic energy, leading to faster movement and potential state changes. Signup and view all the answers

What role do ions play in the particle model of matter?

They are charged particles that can affect the properties of substances. Signup and view all the answers

What defines the behavior of particles in liquids?

Particles can slide past one another while being close together. Signup and view all the answers

What happens to solutes in relation to concentration gradients?

Solutes move from areas of higher to lower concentration until equilibrium is reached. Signup and view all the answers

What characterizes particles in a gas state?

Particles are far apart and move freely in any direction. Signup and view all the answers

What determines the properties of a material in the particle model of matter?

The type of particles and their arrangement. Signup and view all the answers

What is the primary role of ribosomes in a cell?

Synthesize proteins Signup and view all the answers

Which organelle is responsible for producing ATP through cellular respiration?

Mitochondria Signup and view all the answers

Which structure in a cell is primarily involved in protein modification and packaging?

Golgi apparatus Signup and view all the answers

What is the main function of the cell membrane?

Control the movement of substances Signup and view all the answers

Which type of transport requires energy to move substances against their gradient?

Active transport Signup and view all the answers

What appearance do centrioles have, and what is their primary role?

Cylindrical structures, involved in cell division Signup and view all the answers

What characteristic of the phospholipid bilayer contributes to selective permeability?

Semi-permeable barrier Signup and view all the answers

Which kingdom of life includes multicellular organisms that perform photosynthesis?

Plantae Signup and view all the answers

Study Notes

Refinement of Modern Cell Theory

Electron microscope invention in the 1930s provided detailed visualization of cellular organelles, enhancing modern cell theory.

Scientific Inquiry Components

Manipulated Variable (Independent Variable): Intentionally altered to observe effects.
Responding Variable (Dependent Variable): Measured outcomes in reaction to changes in the manipulated variable.
Controlled Variables (Constants): Factors kept consistent to ensure observed changes stem solely from the manipulated variable.

Microscopy Techniques

Bright Field Microscopes: Early types using compound lenses, enabling viewing of living cells.
- Advantages: True specimen color, easy to use, cost-effective.
- Disadvantages: Limited magnification, may require oil immersion lenses.
Simple Microscope: Utilizes a single lens for magnification with a double convex lens.
Dark Field Microscopes: Ideal for pale objects, enhancing contrast with scattered light.
Phase Microscopes: Best for observing living organisms without staining. Uses phase shifts of light for contrast.
Fluorescent Microscopes: Employ UV light, exciting specimens to emit visible wavelengths, useful for identifying pathogens and proteins.
Stereo Microscopes: Designed for dissecting large specimens.

Cellular Structures and Functions

Endoplasmic Reticulum (ER):
- Rough ER: Synthesizes proteins.
- Smooth ER: Synthesizes lipids.
Ribosomes: Small structures synthesizing proteins, found free-floating or attached to the ER.
Golgi Apparatus: Stacked membranes modifying and packaging proteins and lipids for transport.
Animal Cells:
- Cell Membrane: Thin layer controlling substance movement.
- Nucleus: Membrane-bound structure containing DNA, regulating cellular activities.
- Mitochondria: Bean-shaped organelles producing ATP via cellular respiration.
- Centrioles: Cylindrical structures aiding in cell division.
Lysosomes: Organelles filled with enzymes for digestion of waste and cellular debris.

Five Kingdoms of Life

Monera: Prokaryotic single-celled organisms (bacteria).
Protista: Mostly eukaryotic single-celled organisms (amoebas, algae).
Fungi: Eukaryotic organisms that absorb nutrients (molds, yeasts).
Plantae: Eukaryotic multicellular organisms performing photosynthesis.
Animalia: Eukaryotic multicellular organisms that consume organic matter.

Role of Cell Membrane

Structure: Phospholipid bilayer and embedded proteins create a semi-permeable barrier.
Selective Permeability: Facilitates regulated material exchange, maintaining internal stability.

Transport Mechanisms

Passive Transport: No energy required (e.g., diffusion, osmosis).
Active Transport: Requires energy to move substances against concentration gradient.
Concentration Solutions Impact:
- Hypertonic Solution: Higher solute concentration outside the cell causes water to exit, possibly leading to cell shrinkage.
- Hypotonic Solution: Lower solute concentration outside the cell causes water to enter, potentially causing cell swelling or bursting.

Types of Active Transport

Primary Active Transport: Direct ATP use (e.g., Sodium-Potassium Pump).
Secondary Active Transport: Utilizes energy from primary transport (includes symport and antiport).
Bulk Transport: Movement through vesicles involving endocytosis and exocytosis for large particles or volumes.

Particle Model of Matter

All matter consists of small particles (atoms, molecules, ions) which determine material properties.
States of Matter:
- Solid: Particles are tightly packed and fixed in place.
- Liquid: Particles close together but can slide, maintaining volume but adapting shape.
- Gas: Particles widely dispersed, filling their container with no fixed shape or volume.

Concentration Gradients

Substances move from high to low concentration across barriers, influenced by solute movement until equilibrium is achieved.

Auxin Hormones and Plant Responses

Auxins accumulate on the shaded side of the plant, promoting growth towards light (phototropism).
Gravitropism: Roots respond to gravity by growing downward (positive gravitropism), regulated by auxin distribution affecting growth rates in roots and stems.

Conclusion

Both phototropism and gravitropism illustrate how plants adapt to environmental stimuli through hormonal action and cellular mechanisms.

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Description

Explore the advancements in modern cell theory and microscopy techniques in this quiz. Learn about the impact of the electron microscope and the components of scientific inquiry. Test your knowledge on various types of microscopes, their advantages, and disadvantages.