Biology Diffusion Quiz

Diffusion and Concentration

• Simple diffusion rate increases with substance concentration.
• Facilitated diffusion has a constant rate regardless of concentration.
• Rate of facilitated diffusion is limited by the number of available carrier proteins and their operational speed.

Messenger RNA (mRNA) Functions

• Delivers instructions for assembling amino acids into polypeptide chains.
• Not involved in long-term storage of genetic instructions.

Charge in Physiology

• Charge refers to having an excess of electrons or protons.

RNA Differences

• RNA incorporates uracil instead of thymine, which is present in DNA.

Hyaline Cartilage Locations

• Found in structures such as the external ear, epiglottis, laryngeal cartilages, and joint surfaces of bones.

Energy for Ion Concentration

• Concentrating an ion by a factor of 100,000 requires significant energy investment.

Bone Stress Types

• Bones can experience various stresses such as torsion, compression, tension, and shear.

Structural Proteins in Bone

• Collagen is a primary rope-like protein providing tensile strength in bones.

Primary vs. Secondary Bone

• Primary bone is stronger than secondary bone but is completely replaced within the first year of life.

Role of the Inflammatory Phase in Bone Repair

• Generates a provisional callus as part of the bone healing process.

Characteristics of Woven Bone

• Woven bone is disorganized and less strong compared to lamellar bone.

Osteoclast Function

• Responsible for breaking down bone tissue during remodeling.

Elastic vs. Plastic Deformation

• The yield strength indicates the transition point from elastic to plastic deformation.

Hydroxyapatite Formation

• Phosphate is crucial for hydroxyapatite synthesis in bones.

Muscle Contraction Proteins

• Actin and myosin undergo conformational changes during muscle contraction.

Role of Acetylcholine

• Facilitates muscle contraction by propagating action potentials through sodium ion channels.

Sarcomere Striation

• Sarcomeres align myosin and actin, creating a striated appearance in muscle tissues.

Protein Interaction in Muscle Contraction

• Tropomyosin covers actin binding sites, preventing myosin from binding during muscle relaxation.

ATP in the Cross-Bridge Cycle

• ATP causes myosin to change shape, allowing it to detach from actin.

I-Band in Sarcomere

• Composed of actin molecules aligned with Z-discs and lacks myosin.

Muscle Contraction Covering

• Epimysium is the connective tissue sheath covering entire muscles.

Slow Twitch Muscle Fibers

• Characterized by fatigue resistance and significant mitochondrial density for endurance.

Sarcoplasmic Reticulum Role

• Pumps calcium ions back into itself after muscle contraction ends to relax the muscle.

Action Potential Mechanics

• Involves the rapid influx and efflux of sodium and potassium ions across the membrane.

Sarcomere Tension Generation

• Stretched sarcomeres create fewer cross-bridges between actin and myosin, reducing tension.

Motor Unit Structure

• A motor unit consists of muscle fibers linked to a single motor neuron.

Dense Bodies in Smooth Muscle

• Hold together actin filaments and facilitate contraction in smooth muscle.

Ca²+ and K⁺ Channels in Cardiac Action Potential

• Their simultaneous opening maintains depolarization during ventricular action potentials.

Sinus Node Threshold

• The threshold is the membrane voltage required to initiate an action potential.

Self-Stimulation of Sinus Node

• Gradual influx of Ca²+ and Na⁺ ions leads to depolarization and triggers action potentials.

Smooth Muscle Characteristics

• Contracts strongly and for longer durations compared to skeletal muscle, controlled involuntarily.

Test your understanding of simple and facilitated diffusion with this quiz. Explore how the concentration of substances affects the rate of diffusion and differentiate between the two processes. Perfect for students studying cell biology or general biology.