Biology Module 1: The Cell

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Questions and Answers

What is the primary function of the cell membrane?

Regulates materials entering and exiting the cell (correct)

Produces energy for the cell

Stores genetic material

Synthesizes ribosomes

Which of the following components makes up the largest percentage of the cell membrane?

Phospholipids (correct)

Carbohydrates

Cholesterol

Proteins

What is the primary role of the nucleolus within the nucleus?

Assembles ribosomes (correct)

Synthesizes lipids

Controls cell division

Regulates DNA replication

What is diffusion?

Movement of molecules under a concentration gradient Signup and view all the answers

Which cell type is described as large, thin, flat, and containing a rounded nucleus?

Squamous cell Signup and view all the answers

What percentage of the cell membrane is composed of proteins?

55% Signup and view all the answers

Which transportation process does NOT involve water?

Diffusion Signup and view all the answers

Which function is NOT associated with the cell membrane?

Assembly of ribosomes Signup and view all the answers

How are the layers of the cell membrane primarily arranged?

Two layers of phospholipids Signup and view all the answers

Which term refers to the movement of water through a semi-permeable membrane?

Osmosis Signup and view all the answers

What process describes the movement of solvent molecules from a region of lower concentration to one of higher concentration?

Osmosis Signup and view all the answers

Which of the following factors does NOT affect the rate of diffusion?

Presence of enzymes Signup and view all the answers

What term refers to the separation of molecules based on size through a semipermeable membrane?

Dialysis Signup and view all the answers

During osmosis, what happens when equal concentrations are reached on both sides of the membrane?

Movement of solvent molecules stops Signup and view all the answers

Which test is used to identify the presence of amino acids?

Ninhydrin test Signup and view all the answers

What results from the Biuret test indicate the presence of compounds with two or more peptide bonds?

Rose-violet color Signup and view all the answers

Which solution has the same osmotic pressure as another solution, particularly within a cell?

Isotonic solution Signup and view all the answers

What compound observed in the Biuret test indicates a higher number of peptide bonds?

Deep purple color Signup and view all the answers

In which scenario would the movement of solvent molecules during osmosis stop?

When pressure is applied to the weaker solution side Signup and view all the answers

Which of the following statements about dialysis is accurate?

It primarily separates small solutes from larger solutes. Signup and view all the answers

What characterizes a hypotonic solution?

It has a lower osmotic pressure than a particular fluid. Signup and view all the answers

Which of the following actions best describes hydrolysis?

The breaking down of substances through the use of water. Signup and view all the answers

What is the effect of soap on the surface tension of water?

It decreases the surface tension significantly. Signup and view all the answers

Which of the following substances is known to increase surface tension?

Inorganic salts such as NaCl Signup and view all the answers

Surface tension in liquids is primarily caused by which of the following?

The cohesive properties between molecules at the liquid's surface. Signup and view all the answers

What happens to the surface tension when soap is added to water?

It decreases significantly. Signup and view all the answers

A hypertonic solution can be defined as:

A solution with a greater concentration of solute particles outside the membrane. Signup and view all the answers

Which statement about water's surface tension is correct?

It allows for heavier objects to float on its surface. Signup and view all the answers

An example of a solute that lowers surface tension is:

Detergents Signup and view all the answers

What occurs to a cell placed in a hypotonic solution?

The cell swells and may burst from water influx. Signup and view all the answers

Study Notes

Cell Membrane

Also known as the Plasma Membrane, the cell membrane is semi-permeable and selective in its functions.
Composed of 55% proteins, 25% phospholipids, 13% cholesterol, 4% other lipids, and 3% carbohydrates.
Regulates the entry and exit of materials, crucial for cell function and biosynthesis.

Squamous Cell

Characterized by being large, thin, and flat, containing a rounded nucleus.
Functions primarily in absorption and transport of materials, important in areas like the kidneys and alveoli of the lungs.
Plays significant roles in processes such as diffusion, osmosis, and filtration.

Nucleus

Acts as the control center of the cell, regulating the actions of DNA and RNA.

Nucleolus

Located within the nucleus, the nucleolus assembles ribosomes and is the site of ribosomal biogenesis.

Transport Systems Across the Membrane

Various mechanisms include diffusion, osmosis, dialysis, hydrolysis, and surface tension.

Diffusion

The movement of molecules from higher to lower concentration until equilibrium is achieved.
Rate influenced by concentration difference, size and shape of molecules, and temperature.

Osmosis

Movement of solvent molecules from lower to higher concentration through a semi-permeable membrane.
Equilibrium occurs when concentrations equalize or pressure is applied.

Dialysis

A separation process based on the size of molecules, allowing small solutes to pass while retaining larger solutes, typically preventing protein passage.

Dialysis Test Procedures

Test for Chlorides:
- Reacts with AgNO3 to produce a white precipitate (AgCl).
Biuret Test for Peptide Bonds:
- Positive result indicated by a rose-violet-purple color; deeper colors indicate more peptide bonds.
Ninhydrin Test for Amino Acids:
- Positive result manifests as blue to violet color (Ruhemann's purple), except for proline which yields a yellow color.

Types of Solutions

Isotonic Solution: Equivalent osmotic pressure as body fluids, maintaining cell integrity.
Hypotonic Solution: Lower osmotic pressure compared to body fluids, can cause cells to swell.
Hypertonic Solution: Higher osmotic pressure than body fluids, can lead to cell shrinkage due to water loss.

Hydrolysis

A chemical reaction using water to break chemical bonds in a substance.

Surface Tension

Results from the cohesive forces among liquid molecules at the surface, creating a membrane-like property; pure water has high surface tension.
Inorganic salts increase surface tension while soaps and detergents decrease it, affecting how objects interact with water surfaces.

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Description

This quiz covers the fundamental concepts from Module 1 of Biology, focusing on the structure and function of the cell membrane, including its semi-permeable nature and its role in cellular assembly. Additionally, it highlights the characteristics and functions of squamous cells. Test your knowledge on these essential cellular components!