Cell Biology, Transport Mechanisms, and Human Body Systems

Comprehensive practice flashcards covering cell membrane architecture, passive and active transport, cell organelles, characteristics of living organisms, the six biological kingdoms, and human body organization.

What does the Fluid Mosaic Model state regarding the structure and behavior of cell membranes?

Phospholipids can move around each other like a fluid, while different proteins and molecules are embedded within the bilayer like tiles in a mosaic.

What type of molecule is cholesterol, and what is its role in the cell membrane at low temperatures?

It is a lipid that regulates membrane fluidity; at low temperatures, it keeps the phospholipids spread out.

What role do glycoproteins and glycolipids play on the external surface of the cell membrane?

They act as cellular markers that allow the immune system to recognize the body's cells as "self" and not attack them.

What are the two types of transport proteins in the cell membrane, and which is more specific?

Channel proteins and carrier proteins; carrier proteins are more specific in the molecules they can transport.

What is osmosis, and what does dynamic equilibrium describe in an osmotic system?

Osmosis is the passive diffusion of water from a high water concentration to a low water concentration across a semipermeable membrane; dynamic equilibrium occurs when concentrations are equal and water molecules continue moving with no net movement.

How does exposure to a hypotonic solution affect an animal red blood cell versus a hypertonic solution?

In a hypotonic solution, water enters the cell causing it to swell and potentially burst (lysis); in a hypertonic solution, water leaves the cell, causing it to shrivel and appear spiky.

What is the physical condition of a plant cell placed in a hypotonic solution compared to a hypertonic solution?

In a hypotonic solution, cytoplasm exerts pressure on the cell wall making the cell turgid (its normal state); in a hypertonic solution, the cell is plasmolysed as the cytoplasm pulls away from the wall and the vacuole shrinks.

What is the highest value of water potential, and in what direction does water move in terms of water potential?

Pure water has the highest water potential of $0\text{ bar}$, and water always moves from an area of higher water potential to an area of lower water potential.

Which cellular organelle is depicted in this image, and what is its primary function?

Chloroplast; it serves as the site of photosynthesis in plant cells.

Which cellular organelle is illustrated in this image, and what role does it perform?

Golgi Bodies; they modify, sort, and ship proteins within eukaryotic cells.

What organelle structure is depicted here, and what function does it carry out in animal cells?

Centrosome / Centrioles; they create spindle fibers during cell division.

How do the functional roles of the Rough Endoplasmic Reticulum and Smooth Endoplasmic Reticulum differ?

The Rough Endoplasmic Reticulum makes and transports proteins, whereas the Smooth Endoplasmic Reticulum makes lipids and membranes.

Which cell organelles and structures are present in prokaryotic cells?

Cell membrane, cytoplasm, ribosomes, and cell wall.

How many universal characteristics must an organism exhibit to be considered alive, and what are they?

All $8$ characteristics: cells, reproduction, growth and development, homeostasis, metabolism, response to stimuli (irritability), heredity (DNA), and adaptation through evolution.

What is the biological distinction between growth and development in organisms?

Growth is an increase in size and number of cells through division, while development is the process of changing and becoming more complex.

How do sweating and shivering maintain homeostasis in humans?

Sweating cools the body down in hot environments, while shivering generates heat to warm the body in cold environments.

What physical adaptations enable polar bears to survive in the Arctic environment?

A thick layer of fat, thick white fur, small ears, and large paws.

What is the correct sequence of structural organization in the human body from simplest to most complex?

Organelle $\rightarrow$ cell $\rightarrow$ tissue $\rightarrow$ organ $\rightarrow$ organ system $\rightarrow$ organism.

Approximately how many cells are in the human body, and what are the four basic tissue types?

Over $100\text{ trillion}$ cells; the four basic tissue types are connective, epithelial, muscle, and nervous tissue.

What are the major organs and functions of the Integumentary and Endocrine systems?

The Integumentary system consists of the skin and provides a protective barrier; the Endocrine system consists of glands and produces hormones that regulate the body.

What are the major organs and primary functions of the Immune and Excretory systems?

The Immune system contains lymph nodes, spleen, and glands to protect against infection; the Excretory system contains kidneys to remove metabolic wastes.

What cellular characteristics and reproductive modes do Archaebacteria and Eubacteria share?

Both kingdoms consist of prokaryotic, unicellular organisms that reproduce asexually and include both autotrophic and heterotrophic species.

How do the nutritional strategies and reproductive methods of Kingdom Protista compare to Kingdom Fungi?

Protista includes autotrophs and heterotrophs that reproduce mostly asexually (some sexually); Fungi are exclusively heterotrophic consumers that reproduce both asexually and sexually.

How do Kingdom Plantae and Kingdom Animalia differ in their mode of nutrition and reproduction?

Plantae are autotrophic producers that reproduce both asexually and sexually; Animalia are heterotrophic consumers that obtain food from plants and other animals and reproduce sexually.

What is diffusion, and what are two physiological examples of it in the human body?

Diffusion is the passive net movement of particles down a concentration gradient from high to low concentration; examples include gas exchange in the lungs ($O_2$ into blood, $CO_2$ out) and nutrient absorption from digested food in the small intestine into the bloodstream.

Why can small nonpolar molecules cross the cell membrane directly while large polar molecules require facilitated diffusion?

The membrane interior is hydrophobic, allowing small lipid-soluble nonpolar molecules to slip between phospholipids; large polar molecules and ions require transport proteins with hydrophilic interiors.

What four factors directly increase or regulate the rate of diffusion across a surface?

A steeper concentration gradient, greater surface area, thinner exchange surface, and higher temperature.

What defines active transport, and what three fundamental requirements are necessary for it to occur?

Active transport moves substances against their concentration gradient (low to high concentration); it requires energy input (such as ATP), a cell membrane, and transport carrier proteins.

How do endocytosis and exocytosis transport bulk macromolecules across a cell membrane?

Endocytosis folds the cell membrane inward to enclose external molecules within new vesicles; exocytosis fuses internal vesicles with the cell membrane to release macromolecules into the extracellular space.

What sequence of ion binding and phosphorylation occurs during one cycle of the sodium-potassium pump?

Three $Na^+$ ions bind from the inside, triggering phosphorylation by ATP which causes the pump to open outward and release $Na^+$; two $K^+$ ions then bind from the outside, releasing the phosphate group and reverting the pump to release $K^+$ inside.

What is the biological purpose of the sodium-potassium pump, and how do potassium channels assist it?

It maintains the resting membrane potential by creating an electrochemical gradient; potassium channels allow $K^+$ ions to diffuse out, making the inside of the cell more negative than the outside.