Biology Chapter: Cell Membranes and Solutions

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Questions and Answers

What is the primary role of glucose in biological organisms?

To serve as the main source of energy (correct)

To store long-term energy

To serve as a structural component of cell walls

To facilitate photosynthesis

What type of polysaccharide serves as a structural component in plants?

Starch

Glycogen

Chitin

Cellulose (correct)

Which organelle is responsible for photosynthesis in plant cells?

Mitochondria

Endoplasmic reticulum

Nucleus

Chloroplasts (correct)

What evidence supports the endosymbiotic theory regarding chloroplasts?

Chloroplasts have their own distinct DNA similar to bacterial DNA Signup and view all the answers

What is the role of thylakoids in chloroplasts?

To absorb light energy during photosynthesis Signup and view all the answers

Which hormone class is responsible for regulating the balance of Na+ and K+ ions in the body?

Mineralocorticoids Signup and view all the answers

What role do antibodies serve in the immune system?

Fight off pathogens Signup and view all the answers

Which statement about proteins is FALSE?

Proteins are made solely of essential amino acids. Signup and view all the answers

What is the primary function of structural proteins?

Provide strength and shape to structures Signup and view all the answers

Which components make up nucleic acids?

5 carbon sugar, phosphoric acid, and a nitrogenous base Signup and view all the answers

Which of the following is NOT a type of protein function mentioned?

Enzymatic Signup and view all the answers

What is the role of transport proteins in the body?

Carry small particles to different parts of the body Signup and view all the answers

Which statement best describes glucocorticoids?

They control glucose metabolism. Signup and view all the answers

What characterizes passive transport?

Involves the movement of molecules without added energy Signup and view all the answers

What is the primary difference between diffusion and osmosis?

Osmosis is the movement of water only through a selectively permeable membrane Signup and view all the answers

Facilitated diffusion relies on which of the following to assist the movement of molecules?

Protein channels in the cell membrane Signup and view all the answers

In a hypertonic solution, the movement of water will primarily lead to what outcome for the cell?

Water leaves the cell, causing it to shrink Signup and view all the answers

Which solution would be described as isotonic to a cell?

A solution with the same concentration of solute as the cell's interior Signup and view all the answers

What type of transport would glucose utilize to enter a cell?

Facilitated diffusion with protein channels Signup and view all the answers

What determines the flow of water during osmosis?

The osmotic pressure gradient between two solutions Signup and view all the answers

What is the primary function of DNA in cells?

Stores genetic information Signup and view all the answers

When a cell is placed in a hypotonic solution, what happens?

Water moves into the cell causing it to swell Signup and view all the answers

Which nitrogenous base is unique to RNA?

Uracil Signup and view all the answers

Which of the following is NOT a major event in the process of photosynthesis?

Water is split into glucose Signup and view all the answers

What sugar do plants produce during photosynthesis?

Glucose Signup and view all the answers

What is the role of photoautotrophs in an ecosystem?

Make their own food using sunlight Signup and view all the answers

What are the components of a nucleotide?

5-carbon sugar, phosphate, nitrogenous base Signup and view all the answers

What do consumers depend on for their energy needs?

Photosynthesis of producers Signup and view all the answers

Which sugar is classified as a simple sugar?

Glucose Signup and view all the answers

What is the primary function of lipids in biological systems?

Act as a source of energy Signup and view all the answers

Which type of fatty acid is typically solid at room temperature?

Saturated Signup and view all the answers

What characteristic defines phospholipids?

They have both hydrophilic and hydrophobic regions Signup and view all the answers

What is a key feature of trans fats?

They increase the risk of diabetes Signup and view all the answers

What makes steroids different from other lipids?

They have a complex four-ring structure Signup and view all the answers

Which of the following lipids serves as a protective coating in organisms?

Waxes Signup and view all the answers

How do unsaturated fatty acids differ from saturated fatty acids?

They contain one or more double bonds Signup and view all the answers

What role do sex hormones play in the body?

They are responsible for reproduction and secondary sex characteristics Signup and view all the answers

Which type of carbohydrate is characterized by having 3-10 monosaccharides?

Oligosaccharides Signup and view all the answers

What is the primary role of starch in plants?

Energy storage Signup and view all the answers

Which polysaccharide is known to make up a significant portion of plant biomass and is not digestible by humans?

Cellulose Signup and view all the answers

Which polysaccharide serves as a storage form of glucose in animals?

Glycogen Signup and view all the answers

What distinguishes chitin from cellulose?

Chitin contains N-acetyl-D-glucosamines. Signup and view all the answers

Which structure uniquely characterizes glycogen?

Bush-like with branch points every 8-12 glucose residues Signup and view all the answers

Which of the following properties does cellulose possess?

It is the most abundant organic compound on earth. Signup and view all the answers

Which of the following best describes polysaccharides?

They are long chains of monosaccharide units linked by glycosidic bonds. Signup and view all the answers

Study Notes

Solutions

Mixture of 2 or more substances mixed evenly

Concentration

Amount of solute in a solution

Concentration Gradient

Gradual difference in solute concentration between 2 regions in a solution

Cell Membrane & Cell Wall

All cells have a cell membrane made from proteins and lipids
Some cells have cell walls (e.g., plants, fungi, bacteria)
Cell walls are made of cellulose (plants) or other materials
Cell membranes and cell walls are porous, allowing water, carbon dioxide, oxygen, and nutrients to pass through easily
Cell membrane functions to separate a cell's components from its environment
It acts as a gatekeeper, regulating the flow of materials in and out of the cell
Helps maintain homeostasis, the cell's internal balance

Phospholipids

Main component of cell membranes.
Arranged in a bilayer, acting as a barrier to water-soluble molecules.
Amphipathic, having both hydrophilic (water-loving) and hydrophobic (water-fearing) parts.
Structure consists of a head (phosphate group) and two tails (fatty acids); the head is polar/hydrophilic while the tails are non-polar/hydrophobic.

Types of Transport

Passive Transport

No added energy required
Examples include diffusion, osmosis, and facilitated diffusion

Diffusion

Movement of small particles across a selectively permeable membrane from high to low concentration until equilibrium is reached.
Occurs in all states of matter.

Osmosis

Diffusion of water through a selectively permeable membrane from high to low water concentration.
Only the solvent crosses the membrane
Occurs only in liquid states

Facilitated Diffusion

Movement of larger molecules (e.g., glucose) through the cell membrane through protein channels.
Specific transmembrane integral proteins are used to help these larger molecules across the membrane.

Tonicity

A measure of effective osmotic pressure gradient, indicating the water potential differences between two solutions separated by a semipermeable membrane.

Active Transport

Movement of substance against its concentration gradient (low to high concentration)
Requires added energy, often from ATP
Membrane pumps involve carrier proteins using ATP to move substances.

Endocytosis

Active transport process to move particles (large molecules, parts of cells, or even whole cells) into a cell.
Involves the cell membrane folding inward to enclose the material and pinching off into vesicles.
Vesicles then fuse with lysosomes or other organelles for further processing.
- Phagocytosis is a type of endocytosis used to engulf and destroy larger particles

Exocytosis

Active transport process to export large molecules outside of a cell.
Vesicles containing the molecules fuse with the cell membrane and release their contents

Cell Membrane Components

Cholesterol: maintains membrane fluidity and stability at different temperatures

Biomolecules

Basic components of life forms that are essential for growth and maintenance
- Carbohydrates
  - Organic molecules made of Carbon, Hydrogen, and Oxygen
  - Important source of energy to many organisms, including humans
- Monosaccharides
  - Simplest carbohydrates
  - Classified by the number of carbon atoms
  - Glucose (dextrose, blood sugar) - most abundant monosaccharide
  - Fructose - twice as sweet as sucrose
  - Galactose - brain sugar
- Disaccharides
  - Formed when two monomers are linked with the loss of a water molecule
    - Examples include sucrose (table sugar), lactose (milk sugar), and maltose (malt sugar)
- Polysaccharides
  - Long chains of monosaccharides
    - Examples include starch, glycogen, and cellulose

Lipids

Nonpolar organic compounds
- Waxes
- Phospholipids
  - Composed of phosphate head and two fatty acid tails
- Steroids
  - Built from the basic four ring steroid structure
  - Examples include sex hormones, adrenocortical hormones.

Proteins

Biomolecules composed of amino acid units
Essential for various functions in organisms
- Transport proteins, structural proteins, Antibodies, Receptors

Nucleic Acids

Biopolymers essential for information storage and transmission
- DNA and RNA are two major types of nucleic acids

Photosynthesis

Process by which plants convert solar energy into chemical energy
Three main stages
1. Sunlight converted into chemical energy
2. Water is split into oxygen
3. Carbon dioxide is fixed into sugars (glucose)
- Light-dependent reactions occur in thylakoids
  - Capture light energy for chemical energy conversions
- Light independent reactions (Calvin cycle) occur in stroma
  - Carbon dioxide is converted into sugars

Cellular Respiration

Process that releases chemical energy from carbohydrates
Aerobic respiration (occurs with oxygen)
Glycolysis —> Krebs Cycle —> Electron Transport Chain
Anaerobic respiration (occurs without oxygen) – Glycolysis —>Fermentation
Produces ATP (energy currency for cells)

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Description

Explore the fundamentals of cell membranes, solutions, and concentration gradients in this quiz. Learn about the composition of cell membranes, the role of phospholipids, and how substances move through these cellular structures. Test your understanding of these key biological concepts.