Biology chapter 2
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Questions and Answers

Which of the following is NOT a major organic compound group?

  • Proteins (correct)
  • Nucleic Acids
  • Carbohydrates
  • Lipids

All cells contain a cell wall.

False (B)

What is the primary function of the mitochondria?

Cellular respiration

What type of transport requires additional energy?

<p>Active transport (C)</p> Signup and view all the answers

The main component of genetic material is __________.

<p>DNA</p> Signup and view all the answers

Passive transport does not require additional energy.

<p>True (A)</p> Signup and view all the answers

What structure directs all cellular activities?

<p>Nucleus (B)</p> Signup and view all the answers

Match the following organelles with their functions:

<p>Cell Membrane = Protective membrane allowing transport Golgi Apparatus = Packages substances for transport Ribosomes = Synthesize proteins Cytoplasm = Suspends organelles and nutrients</p> Signup and view all the answers

What is the term for proteins that assist in moving substances against the concentration gradient?

<p>pumps</p> Signup and view all the answers

The cytoskeleton helps maintain the shape of the cell.

<p>True (A)</p> Signup and view all the answers

Active transport requires energy in the form of __________.

<p>ATP</p> Signup and view all the answers

Granules where amino acids are combined to make _______ are called ribosomes.

<p>proteins</p> Signup and view all the answers

Which process allows large molecules to enter a cell?

<p>Endocytosis (B)</p> Signup and view all the answers

Exocytosis is a process that brings materials inside the cell.

<p>False (B)</p> Signup and view all the answers

What do you call the process of a vesicle fusing with the cell membrane to release contents outside the cell?

<p>Exocytosis</p> Signup and view all the answers

Match the following processes with their descriptions:

<p>Endocytosis = Bringing substances into the cell Exocytosis = Releasing substances out of the cell Active Transport = Moving substances against the concentration gradient Passive Transport = Moving substances with the concentration gradient</p> Signup and view all the answers

What is the primary function of the cell membrane?

<p>To maintain equilibrium inside the cell (D)</p> Signup and view all the answers

The cell membrane is an impermeable barrier that does not allow any substances to pass through.

<p>False (B)</p> Signup and view all the answers

What does the term 'semi-permeable' mean in relation to the cell membrane?

<p>A semi-permeable membrane only allows certain substances to pass through.</p> Signup and view all the answers

The cell membrane consists of a ___________________________ bilayer.

<p>phospholipid</p> Signup and view all the answers

Match the terms related to the cell membrane with their definitions:

<p>Permeable = Allows substances to pass through Impermeable = Does not allow anything to pass through Hydrophilic = Attracted to water Hydrophobic = Repelled by water</p> Signup and view all the answers

What type of molecules are phospholipids composed of?

<p>Both hydrophilic and hydrophobic regions (B)</p> Signup and view all the answers

The heads of phospholipids are hydrophobic and face outward in the bilayer.

<p>False (B)</p> Signup and view all the answers

Lipids are _____________________ and they hate water.

<p>hydrophobic</p> Signup and view all the answers

If the attachment point on the receptor protein is ____________________, the virus will not be able to enter the cell.

<p>blocked</p> Signup and view all the answers

What are the two types of dialysis?

<p>Peritoneal and Hemodialysis (C)</p> Signup and view all the answers

Toxins and wastes are normally eliminated by healthy kidneys during the dialysis process.

<p>False (B)</p> Signup and view all the answers

What is the purpose of dialysis?

<p>To rid the blood of toxins, wastes, and excess fluid.</p> Signup and view all the answers

Both types of dialysis are based on the principles of ____________________ and ____________________.

<p>diffusion, osmosis</p> Signup and view all the answers

Match the components of peritoneal dialysis with their functions:

<p>Peritoneum = Lines the abdominal cavity Catheter = Delivers dialysate fluid Dialysate fluid = Cleanses the blood Waste material = Diffuses into dialysate fluid</p> Signup and view all the answers

In peritoneal dialysis, what is the composition of the dialysate fluid compared to human body fluids?

<p>Similar to human body fluids (A)</p> Signup and view all the answers

What happens to waste materials in the blood during dialysis?

<p>They diffuse across the membrane into the dialysate fluid.</p> Signup and view all the answers

The patient is able to perform peritoneal dialysis at _____________ while carrying out most daily activities.

<p>home</p> Signup and view all the answers

In which type of dialysis is blood physically removed from the body, cleansed, and then returned?

<p>Hemodialysis (B)</p> Signup and view all the answers

Hemodialysis can be performed at home without any supervision.

<p>False (B)</p> Signup and view all the answers

What must reach all parts of the cell?

<p>Nutrients, water, and oxygen</p> Signup and view all the answers

The rate at which materials can enter or leave the cell is limited by the ______________ of the cell membrane.

<p>surface area</p> Signup and view all the answers

As a cell grows larger, what becomes more difficult?

<p>It becomes more difficult for materials to diffuse (D)</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Surface Area = Amount of membrane exposed to the environment Volume = Determines how far materials must move to diffuse Surface Area to Volume Ratio = Indicates transportation potential of a cell Maximize = To enhance surface area relative to the volume</p> Signup and view all the answers

An increase in volume makes it easier for a cell to survive.

<p>False (B)</p> Signup and view all the answers

As the side length of a cube increases, what happens to the surface area to volume ratio?

<p>It decreases (A)</p> Signup and view all the answers

A larger cell can remove waste products and deliver nutrients more efficiently than a smaller cell.

<p>False (B)</p> Signup and view all the answers

What is the primary issue for a very large cell regarding its efficiency?

<p>It has difficulty removing waste and delivering nutrients.</p> Signup and view all the answers

Cells have developed into shapes that maximize their surface area without increasing their ____________ all that much.

<p>volume</p> Signup and view all the answers

Match the following sphere measurements with their corresponding values:

<p>Surface Area (cm²) = 18.0955 cm² Volume (cm³) = 7.238 cm³ SA/V Ratio (cm²/cm³) = 2.5 cm²/cm³ Radius (cm) = 1.5 cm</p> Signup and view all the answers

What mathematical formula is used to calculate the surface area of a sphere?

<p>$SA = 4 \pi r^2$ (C)</p> Signup and view all the answers

The surface area of a sphere increases more rapidly than its volume as the radius increases.

<p>False (B)</p> Signup and view all the answers

What is the SA/V ratio for a sphere with a surface area of 1309 cm² and a volume of 113.097 cm³?

<p>0.3 cm²/cm³</p> Signup and view all the answers

Flashcards

Lipids

A group of organic compounds including fats and oils.

Carbohydrates

A group of organic compounds including sugars, starches, and cellulose.

Proteins

A group of organic compounds essential for building and repairing tissues, like muscle fibres.

Nucleic Acids

A group of organic compounds primarily responsible for storing and transmitting genetic information.

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Cytoskeleton

An internal network of fibres made of proteins and lipids that supports and shapes the cell.

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Cell Membrane

A protective barrier that surrounds the cell, regulating the movement of materials in and out.

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Mitochondria

Organelle responsible for cellular respiration, converting sugars into energy.

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Ribosomes

Organelles where proteins are synthesized from amino acids.

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Passive Transport

Movement of molecules across a cell membrane that does not require energy. This movement follows the concentration gradient, meaning molecules move from an area of high concentration to an area of low concentration.

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Active Transport

Movement of molecules across a cell membrane that requires energy. This movement goes against the concentration gradient, meaning molecules move from an area of low concentration to an area of high concentration.

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Concentration Gradient

The difference in concentration of a substance between two areas. Molecules naturally move from an area of high concentration to an area of low concentration.

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Carrier Protein

A protein embedded in the cell membrane that helps transport molecules across the membrane. It binds to the molecule and facilitates its movement.

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Channel Protein

A protein embedded in the cell membrane that forms a channel or pore through which specific molecules can pass.

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Endocytosis

A process where the cell membrane engulfs a large particle and brings it into the cell.

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Exocytosis

A process where a vesicle containing a particle fuses with the cell membrane and releases the contents outside the cell.

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Vesicle

A small, membrane-bound sac within a cell that transports substances. Vesicles can bud off from the cell membrane or other organelles.

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Cell Membrane's Role

The cell membrane plays a vital role in maintaining equilibrium (balance) within the cell by controlling what enters and leaves.

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Essential Movement

Movement across the cell membrane is crucial for survival, as cells need to acquire essential nutrients, eliminate waste, and communicate with other cells.

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Open System

A cell is considered an open system because it allows for the free flow of both matter (substances) and energy.

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Semi-Permeable Membrane

The cell membrane acts like a selective filter, allowing only certain substances to pass through while blocking others. It's like a bouncer, letting in the 'good' stuff and keeping out the 'bad' stuff.

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Phospholipid Bilayer

The cell membrane is made up of a phospholipid bilayer, a double layer of phospholipid molecules.

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Hydrophilic Head

The phosphate head of a phospholipid is hydrophilic, meaning it loves water and attracts it.

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Hydrophobic Tail

The lipid tail of a phospholipid is hydrophobic, meaning it repels water and avoids it.

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Phospholipid Arrangement

Due to their hydrophilic and hydrophobic properties, phospholipids naturally arrange themselves into a bilayer with the hydrophilic heads facing outward towards the watery environment inside and outside the cell.

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Viral Attachment

The process by which a virus binds to a specific receptor protein on the surface of a host cell, initiating infection.

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Receptor Protein

A protein found on the surface of a cell that serves as a binding site for a virus or other molecule.

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Dialysis

A medical procedure that removes waste products, excess fluids, and toxins from the blood when the kidneys are unable to perform this function.

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Hemodialysis

A type of dialysis that uses an artificial kidney machine to filter the blood.

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Peritoneal Dialysis

A type of dialysis that uses the lining of the abdominal cavity (peritoneum) as a filter.

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Dialysate Fluid

A sterile solution used in dialysis that helps remove waste products and excess fluid from the blood.

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Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

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What is a problem for a large cell?

A larger cell needs more nutrients and oxygen, but these substances might find it difficult to reach all parts of the cell due to the increased distance from the cell membrane. Waste products need to be removed from the cell quickly before they become toxic.

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Surface area to volume ratio

The measure of a cell's surface area relative to its volume. It represents the amount of surface available for exchange of materials compared to the amount of space occupied by the cell.

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How does surface area affect material exchange?

A larger cell surface area means more membrane is exposed to the environment, allowing for more efficient exchange of nutrients, oxygen, and waste products between the cell and its surroundings

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What is the effect of cell growth on surface area to volume ratio?

As a cell grows larger, its volume increases more rapidly than its surface area. This results in a smaller surface area to volume ratio, making it harder for the cell to transport enough substances and eliminate waste efficiently.

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Why is a large surface area to volume ratio ideal for cells?

A large surface area to volume ratio ensures efficient transport of materials into and out of the cell. This helps maintain optimal conditions for cell function and survival.

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Why is a large cell problematic?

Large cells have a smaller surface area to volume ratio, leading to slower transport of materials across the cell membrane. This hinders nutrient delivery, waste removal, and overall cell functioning, potentially causing cell death

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Why is SA:V important for cells?

The surface area to volume ratio affects a cell's efficiency in exchanging materials (nutrients in, waste out) with its environment. A higher SA:V ratio means more efficient exchange.

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How does SA:V change as a cell grows?

As a cell gets larger, its volume increases more rapidly than its surface area. This leads to a smaller SA:V ratio, making it harder for the cell to exchange materials effectively.

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SA:V and cell efficiency

Cells need to maintain a high SA:V ratio for efficient nutrient uptake and waste removal. This is why cells often have specialized shapes or foldings to increase their surface area.

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How do cells maximize SA:V?

Cells have evolved strategies to maximize their surface area without significantly increasing their volume, such as developing folded membranes, projections, or elongated shapes.

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SA:V and cell size limits

The decreasing SA:V ratio with increasing size limits how big a cell can become. To overcome this, organisms often use multicellularity and specialized structures.

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What is the significance of a decreasing SA:V ratio in large single-celled organisms?

It makes it difficult for a large cell to transport nutrients and waste products quickly enough to sustain itself.

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Why is SA:V a problem for large cells?

Large cells have a smaller surface area to volume ratio, resulting in slower nutrient uptake and waste removal, potentially leading to cell death.

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Study Notes

Cell Structure and Function

  • Cells are the basic unit of life, exhibiting increasing complexity from simple to complex structures.
  • Cells facilitate life processes like nutrient intake, growth, responses to stimuli, gas exchange, waste removal, and reproduction.
  • Two basic types are prokaryotes (lacking a nucleus) and eukaryotes (containing a nucleus).
  • Prokaryotes are single-celled organisms with a simple structure, lacking membrane-bound organelles.
  • Eukaryotes are larger and can be single or multicellular, containing a nucleus and numerous membrane-bound organelles.

Chemical Composition of Cells

  • Major elements in plant and animal cells are carbon, hydrogen, oxygen, and nitrogen.
  • These elements form four major organic compounds: lipids (fats and oils, sugars, starches, cellulose), proteins, carbohydrates, and nucleic acids (primary component of genetic material).
  • Both plant and animal cells have an internal protein and lipid network called the cytoskeleton, supporting the cell structure.

Cell Organelles

  • Organelles are specialized structures within cells performing specific functions.
  • Cell membrane: A protective membrane controlling material transport in and out of the cell.
  • Cell wall (plant cells only): Provides strength and support.
  • Cytoplasm (cytosol): Gel-like substance containing organelles and nutrients.
  • Nucleus: Directs cellular activities, containing DNA.
  • Mitochondria: Site of cellular respiration, converting chemical energy in sugars into usable energy for the cell.
  • Golgi apparatus: Receives, processes, and packages substances for transport.
  • Ribosomes: Where proteins are synthesized.
  • Endoplasmic reticulum (ER): System of interconnected tubes for material transport throughout the cell. Rough ER has ribosomes, involved in protein synthesis; smooth ER involved in lipid synthesis.
  • Vacuoles and vesicles: Often involved in storage and transport of substances. Large central vacuole in plant cells stores water.
  • Chloroplasts (plant cells only): Site of photosynthesis, converting light energy into chemical energy.
  • Lysosomes (animal cells only): Contain enzymes crucial for breaking down and recycling cellular components.
  • Centrioles (animal cells only): Involved in cell division.

Lesson 2.2: The Role of the Cell Membrane in Transport

  • Cell membranes maintain internal equilibrium (balance).
  • Semi-permeable, allowing some materials to pass through but not others.
  • Phospholipid bilayer is the primary structure.
  • Phospholipids have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails, naturally forming a bilayer
  • Fluid mosaic model describes the cell membrane's structure as a fluid and dynamic arrangement of various components.
  • Proteins (channel, carrier) embedded in the membrane assist in specific substance transport across the membrane
  • Passive transport (diffusion, osmosis) requires no energy, movement with the concentration gradient and Active transport (carrier proteins) needs energy, moving against the concentration gradient

Osmosis

  • Osmosis is water movement across a selectively permeable membrane to equalize solute concentrations between two areas.
  • Water flows from low solute and high water concentration to high solute and low water concentration.
  • Differences in solute concentrations lead to differences in water concentrations
  • These differences create a concentration gradient causing water to move through osmosis.
  • Reverse osmosis is the process of using pressure to pull water through a semi-permeable membrane, removing solutes (like salts) from water.

Solutions and Tonicity

  • Hypertonic solutions have a higher solute concentration than the cell. Water moves out of the cell, causing it to shrink, which might cause cells to die
  • Hypotonic solutions have a lower solute concentration than the cell. Water moves into the cell, causing it to swell. This may cause cells to burst
  • Isotonic solutions have an equal solute concentration as the cell. No net water movement.

Facilitated Transport

  • Substances move through the cell membrane using transport proteins.
  • Channel proteins create passages through the membrane.
  • Carrier proteins change shape to transport substances across the membrane, potentially against a concentration gradient.

Active Transport

  • Active transport moves substances across the cell membrane against their concentration gradient.
  • Energy (ATP) is required.
  • Transport proteins (pumps) are essential for this process.

Endocytosis and Exocytosis

  • Endocytosis takes in large molecules/particles.
  • Vesicles form around the material to bring it into the cell
  • Exocytosis releases materials from the cell

Lesson 2.4: Surface Area and Cell Volume

  • Cell size is limited by the surface area-to-volume ratio.
  • Larger cells have smaller surface area-to-volume ratios and have difficulty transporting materials across the membrane, potentially causing them to die.
  • Multicellular organisms use specialized cell structures to address and overcome this issue like villi and root hairs.

Other relevant concepts

  • Protein hormones affect target cells in the body, regulating various functions
  • Synthetic membrane technologies (e.g., liposomes) mimic natural functions within cells.
  • Dialysis is a medical procedure using diffusion and osmosis to remove waste products from the blood.

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Test your knowledge on key concepts related to cell structure and functions in biology. This quiz covers various organelles, their roles, and types of transport mechanisms. Challenge yourself to identify correct functions and processes involved in cellular activities.

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