Biology Diffusion Quiz

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Questions and Answers

Where is hyaline cartilage primarily found?

Laryngeal cartilages (correct)

Joint surfaces of bone (correct)

External ear (correct)

Epiglottis (correct)

How much energy is needed for a cell to concentrate an ion by a factor of 100,000?

7000 calories per osmole

5600 calories per osmole (correct)

2800 calories per osmole

4200 calories per osmole

Which of the following is NOT a way that bone can be placed under stress?

Shear

Compression

Tension

Cortical (correct)

Which protein is crucial for bone flexibility and resistance to stretching?

Collagen Signup and view all the answers

Which statement about primary bone is true?

It is stronger than secondary bone but is replaced in the first year of life Signup and view all the answers

What is the main purpose of the inflammatory phase of bone repair after a fracture?

Generate a provisional callus Signup and view all the answers

What describes woven bone compared to lamellar bone?

Disorganized and less strong Signup and view all the answers

Which cell type is responsible for breaking down bone tissue during bone remodeling?

Osteoclast Signup and view all the answers

What is the primary function of acetylcholine in skeletal muscle contraction?

Triggers sodium ions to enter the muscle cell, allowing propagation of action potential Signup and view all the answers

What causes skeletal muscle fibers to appear striated under a microscope?

The arrangement of sarcomeres, with myosin and actin in distinct patterns Signup and view all the answers

Which protein is responsible for covering the binding sites on actin?

Tropomyosin Signup and view all the answers

In the cross-bridge cycle, what role does ATP play?

It provides energy for myosin to pull on actin, shortening the sarcomere Signup and view all the answers

What is formed in the 'I-band' of a sarcomere?

Only actin molecules connected to the Z-disc Signup and view all the answers

What connective tissue encases an entire muscle?

Epimysium Signup and view all the answers

Which characteristic is TRUE regarding slow twitch muscle fibers?

They are designed for endurance and are more resistant to fatigue Signup and view all the answers

Which statement describes the structure of a sarcomere?

It contains alternating bands of actin and myosin Signup and view all the answers

What occurs once an action potential is no longer spreading through a motor unit?

Sarcoplasmic reticulum pumps Ca^2+ back into itself Signup and view all the answers

Which statement best describes an action potential?

A wave of Na^+ flowing into the cell followed by a wave of K^+ flowing out of the cell Signup and view all the answers

When a sarcomere is stretched to its maximum length, which statement is TRUE?

Fewer cross bridges connect myosin to actin, and less tension can be generated Signup and view all the answers

Which statement about motor units is TRUE?

All the muscle fibers connected to a single axon must contract at the same time Signup and view all the answers

Which of the following statements about the dense body is true?

In smooth muscle, it holds together a group of actin molecules Signup and view all the answers

When troponin changes shape as a result of Ca^2+ binding to it, what then happens?

Tropomyosin uncovers binding sites on actin Signup and view all the answers

Which of the following is a characteristic of poorly developed oxidative energy pathways?

Few small mitochondria Signup and view all the answers

What is the role of Ca^2+ in muscle contraction?

Ca^2+ binds to troponin, causing tropomyosin to shift Signup and view all the answers

Which statement correctly explains the behavior of Line B in the graph?

The rate of facilitated diffusion is limited by the number of carrier proteins. Signup and view all the answers

What is the primary role of messenger RNA (mRNA) in the cell?

To provide instructions for assembling amino acids into a chain. Signup and view all the answers

Which of the following best defines 'charge' in a physiological context?

Having one or more extra electrons or extra protons. Signup and view all the answers

What replaces thymine in RNA molecules compared to DNA?

Uracil Signup and view all the answers

How does Line A differ from Lines B and C in terms of diffusion rates?

Line A represents constant diffusion rates. Signup and view all the answers

Which statement is true regarding facilitated diffusion?

It is influenced by the number and speed of carrier proteins. Signup and view all the answers

Which of the following describes the primary characteristic of simple diffusion?

It generally increases with concentration. Signup and view all the answers

What describes the limit on the rate of facilitated diffusion?

It is restricted by the number of carrier proteins available. Signup and view all the answers

Which of the following describes the sarcolemma?

Cell membrane of a muscle cell Signup and view all the answers

What is the term for a muscle generating force while simultaneously elongating?

Eccentric contraction Signup and view all the answers

What occurs when Ca^2+ and K^+ channels open at the same time during an action potential in heart tissues?

The cell membrane remains depolarized for 1-2 tenths of a second Signup and view all the answers

What does 'threshold' refer to in the context of a sinus node?

The membrane voltage that initiates an action potential Signup and view all the answers

What process allows the sinus node to self-stimulate?

Ca^2+ and Na^+ slowly diffuse into cells Signup and view all the answers

Which statement about smooth muscle is true?

Fibers can contract more strongly and for a longer time than skeletal muscle Signup and view all the answers

What happens to the myosin and actin molecules during muscle relaxation?

They unbind due to the absence of calcium Signup and view all the answers

During an action potential in the heart, what is the immediate effect of Na^+ channels opening?

The cell membrane depolarizes Signup and view all the answers

Study Notes

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.

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Description

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.