Practice test

Which of the following best defines homeostasis?
a) Maintaining identical conditions in all body tissues
b) Maintaining internal conditions within a normal range despite external change
c) Producing constant energy without feedback
d) Changing external conditions to match the internal state

a) Wrong – the body does not keep every tissue identical.
b) Correct – homeostasis keeps internal variables stable despite external change.
c) Wrong – energy production is not constant and involves feedback.
d) Wrong – organisms adjust internally

Animals are classified as:
a) Autotrophic prokaryotes
b) Multicellular heterotrophic eukaryotes
c) Unicellular autotrophs
d) Photosynthetic protists

a) Wrong – animals are not prokaryotic.
b) Correct – they are multicellular

What is the correct order of organization in animals?
a) Organ → Organ System → Tissue → Cell
b) Cell → Chemical → Organ → Organ System
c) Chemical → Cell → Tissue → Organ → Organ System → Organism
d) Tissue → Chemical → Organ → System

a) Wrong – order is reversed.
b) Wrong – chemical should precede cell.
c) Correct – it shows smallest to largest organization.
d) Wrong – the sequence is mixed

Which tissue type covers body surfaces and lines internal organs?
a) Muscle tissue
b) Epithelial tissue
c) Connective tissue
d) Nervous tissue

a) Wrong – muscle causes movement.
b) Correct – epithelial forms protective linings and coverings.
c) Wrong – connective binds and supports.
d) Wrong – nervous transmits impulses

Which pair of tissues are unique to animals?
a) Connective and epithelial
b) Muscle and nervous
c) Adipose and cartilage
d) Loose and dense connective

a) Wrong – these also occur in some other organisms.
b) Correct – only animals have muscle and nervous tissues specialized for movement and signaling.
c) Wrong – both are connective tissues.
d) Wrong – they are subtypes

What is the function of connective tissue?
a) Transmission of impulses
b) Protection and absorption
c) Binding

support

Which connective tissue connects muscle to bone?
a) Ligament
b) Tendon
c) Cartilage
d) Adipose

a) Wrong – ligaments connect bone to bone.
b) Correct – tendons attach muscle to bone to transfer force.
c) Wrong – cartilage cushions joints.
d) Wrong – adipose stores fat

Which connective tissue connects bone to bone?
a) Ligament
b) Tendon
c) Cartilage
d) Areolar

a) Correct – ligaments stabilize joints by linking bones.
b) Wrong – tendons connect muscles to bones.
c) Wrong – cartilage cushions ends of bones.
d) Wrong – areolar is loose connective tissue under epithelium

The functional unit of nervous tissue is the:
a) Neuroglia
b) Neuron
c) Axon hillock
d) Myofibril

a) Wrong – glia support neurons but don’t send signals.
b) Correct – neurons generate and transmit nerve impulses.
c) Wrong – that’s a part of a neuron.
d) Wrong – myofibrils belong to muscle cells

The control center in a homeostatic feedback loop:
a) Detects stimuli
b) Executes a response
c) Processes information and sends commands
d) Produces hormones

a) Wrong – that’s the receptor’s job.
b) Wrong – that’s the effector.
c) Correct – the control center interprets input and directs response.
d) Wrong – not all control centers secrete hormones

Which of the following is a negative feedback example?
a) Labor contractions
b) Blood clotting
c) Temperature regulation by sweating
d) Childbirth hormone release

a) Wrong – that’s positive feedback.
b) Wrong – clotting is self-amplifying.
c) Correct – sweating reverses temperature change.
d) Wrong – oxytocin release is positive feedback

Which of the following is a positive feedback example?
a) Sweating to cool the body
b) Shivering to warm the body
c) Labor contractions during childbirth
d) Blood sugar regulation

a) Wrong – negative feedback example.
b) Wrong – also negative feedback.
c) Correct – contractions increase until birth occurs.
d) Wrong – blood sugar is negative feedback

What fluid is found inside cells?
a) Plasma
b) Interstitial fluid
c) Intracellular fluid
d) Extracellular fluid

a) Wrong – plasma is outside cells.
b) Wrong – interstitial fluid surrounds cells.
c) Correct – intracellular fluid is the cytoplasm within cells.
d) Wrong – that’s outside cells

What fluid surrounds cells and includes plasma and interstitial fluid?
a) Extracellular fluid
b) Cytosol
c) Intracellular fluid
d) Endoplasmic fluid

a) Correct – it exists outside cells and includes plasma and interstitial components.
b) Wrong – cytosol is inside cells.
c) Wrong – that’s internal fluid.
d) Wrong – no such term

Which solution causes an animal cell to swell?
a) Isotonic
b) Hypertonic
c) Hypotonic
d) None of these

a) Wrong – no net water movement.
b) Wrong – cell shrinks in hypertonic solution.
c) Correct – water enters cell causing it to swell.
d) Wrong – “none” is incorrect

Which solution causes an animal cell to shrink?
a) Isotonic
b) Hypotonic
c) Hypertonic
d) Aquatonic

a) Wrong – balanced solution.
b) Wrong – causes swelling.
c) Correct – water leaves cell making it shrink.
d) Wrong – not a real term

The four tissue types found in animals are:
a) Connective

Bone

Muscle tissue is specialized for:
a) Secretion
b) Protection
c) Contraction and movement
d) Ion storage

a) Wrong – that’s epithelial.
b) Wrong – skin protects.
c) Correct – muscle shortens to produce movement.
d) Wrong – not its main role

Skeletal muscle is:
a) Striated and involuntary
b) Striated and voluntary
c) Smooth and voluntary
d) Non-striated and involuntary

a) Wrong – skeletal is voluntary.
b) Correct – it has bands and is under conscious control.
c) Wrong – smooth is involuntary.
d) Wrong – that describes smooth muscle

Which of the following produces most body heat during shivering?
a) Smooth muscle
b) Cardiac muscle
c) Skeletal muscle
d) Adipose tissue

a) Wrong – smooth muscle controls internal organs

The sensor (receptor) in a feedback system:
a) Produces the response
b) Detects the change or stimulus
c) Determines the set point
d) Sends the motor signal

a) Wrong – the effector makes the response.
b) Correct – receptors sense deviations from normal conditions.
c) Wrong – the control center sets the target range.
d) Wrong – that’s a neuron’s function

Obligatory water loss means:
a) The body never loses water
b) A minimum amount of water is always lost
c) The kidneys can stop water loss completely
d) Water loss only occurs during exercise

a) Wrong – water is always lost.
b) Correct – some water leaves through urine

The largest organ of the body listed in your notes is the:
a) Brain
b) Heart
c) Skin
d) Liver

a) Wrong – the brain is smaller.
b) Wrong – heart is vital but smaller.
c) Correct – skin covers the whole body and is the largest organ.
d) Wrong – liver is the largest internal organ

Which two body systems work together to maintain internal homeostasis?
a) Circulatory and respiratory
b) Digestive and skeletal
c) Nervous and endocrine
d) Reproductive and muscular

a) Wrong – they mainly handle gas exchange.
b) Wrong – unrelated to regulation.
c) Correct – these coordinate chemical and electrical control to keep stability.
d) Wrong – not regulatory

The three main functions of the nervous system are:
a) Motor

reflex

The central nervous system (CNS) consists of:
a) Brain and spinal cord
b) Brain and nerves
c) Spinal nerves and ganglia
d) Sensory and motor neurons

a) Correct – these are the main processing structures.
b) Wrong – nerves belong to the PNS.
c) Wrong – those are peripheral components.
d) Wrong – neuron types

The peripheral nervous system (PNS) includes:
a) Brain only
b) Spinal cord only
c) All nerves and ganglia outside the CNS
d) Only cranial nerves

a) Wrong – that’s CNS.
b) Wrong – also CNS.
c) Correct – it links body to brain and spinal cord.
d) Wrong – it also includes spinal nerves

The cell type that supports

nourishes

Which of the following correctly matches a glial cell with its function?
a) Astrocyte – transmits impulses
b) Oligodendrocyte – forms myelin in CNS
c) Microglia – stores glycogen
d) Ependymal – secretes digestive enzymes

a) Wrong – astrocytes support neurons.
b) Correct – oligodendrocytes produce CNS myelin for insulation.
c) Wrong – microglia perform immune cleanup.
d) Wrong – ependymal cells line ventricles and move CSF

The functional unit of the nervous system is the:
a) Brain
b) Neuron
c) Synapse
d) Glial cell

a) Wrong – organ level

Which part of a neuron receives incoming signals?
a) Axon
b) Cell body
c) Dendrites
d) Myelin sheath

a) Wrong – sends impulses.
b) Wrong – integrates signals.
c) Correct – dendrites receive incoming information.
d) Wrong – insulates axon

The axon of a neuron:
a) Receives impulses
b) Sends impulses away from the cell body
c) Detects stimuli
d) Secretes hormones

a) Wrong – dendrites receive.
b) Correct – axons carry signals to other cells.
c) Wrong – receptors detect stimuli.
d) Wrong – neurons don’t secrete hormones

A myelin sheath:
a) Slows down impulses
b) Increases impulse speed and insulates the axon
c) Prevents action potentials
d) Is made of collagen

a) Wrong – it speeds signals.
b) Correct – myelin boosts conduction and protects axon.
c) Wrong – allows rather than blocks potentials.
d) Wrong – composed of lipids and proteins

Myelinated fibers form:
a) Gray matter
b) White matter
c) Spinal ganglia only
d) Dendritic layers

a) Wrong – gray matter is unmyelinated.
b) Correct – myelin gives white appearance.
c) Wrong – not limited to ganglia.
d) Wrong – not a tissue type

At a chemical synapse

the impulse crosses the gap by means of:
a) Sodium ions only
b) Neurotransmitters
c) ATP
d) Electrical current only

The small space between two neurons is called the:
a) Synaptic cleft
b) Axon hillock
c) Node of Ranvier
d) Dendritic gap

a) Correct – neurotransmitters diffuse across this gap.
b) Wrong – that’s the trigger zone on a neuron.
c) Wrong – nodes are gaps in myelin.
d) Wrong – not a real term

The neurotransmitter that stimulates muscle contraction is:
a) Serotonin
b) Dopamine
c) Acetylcholine (ACh)
d) GABA

a) Wrong – mood regulation.
b) Wrong – controls reward pathways.
c) Correct – ACh binds to muscle receptors to initiate contraction.
d) Wrong – inhibitory neurotransmitter

Which neurotransmitter produces calming or inhibitory effects?
a) GABA
b) Acetylcholine
c) Norepinephrine
d) Serotonin (excitatory type)

a) Correct – GABA reduces neuron firing and induces calm.
b) Wrong – ACh excites muscles.
c) Wrong – norepinephrine stimulates arousal.
d) Wrong – some serotonin is excitatory

The resting membrane potential in a neuron is about:
a) +70 mV
b) –70 mV
c) +30 mV
d) –30 mV

a) Wrong – inside is negative relative to outside.
b) Correct – neuron interior is –70 mV at rest.
c) Wrong – occurs during action potential.
d) Wrong – too small in magnitude

The sodium-potassium pump maintains the resting potential by:
a) Moving Na⁺ out and K⁺ in
b) Moving K⁺ out and Na⁺ in
c) Blocking both ions completely
d) Using diffusion only

a) Correct – the pump actively moves sodium out and potassium in to maintain charge balance.
b) Wrong – the movement is reversed.
c) Wrong – ions are exchanged

During depolarization

the inside of the neuron becomes:
a) More negative
b) More positive as Na⁺ rushes in
c) Unchanged
d) Hyperpolarized

During repolarization

which ion moves out of the neuron?
a) Calcium
b) Sodium
c) Potassium
d) Chloride

The refractory period ensures that:
a) The impulse travels one direction only
b) The neuron can fire repeatedly with no rest
c) Na⁺ channels remain open indefinitely
d) The impulse reverses direction

a) Correct – it prevents immediate re-stimulation so signals go forward only.
b) Wrong – it temporarily prevents refiring.
c) Wrong – channels close during this time.
d) Wrong – opposite of what happens

The reflex arc is the pathway that:
a) Slows motor response
b) Connects receptor to effector through the CNS
c) Only controls brain activity
d) Transports hormones

a) Wrong – reflexes are rapid.
b) Correct – sensory input travels to integration center and out to effector.
c) Wrong – many reflexes bypass brain.
d) Wrong – not hormonal

In a reflex arc

the correct order is:
a) Receptor → Motor neuron → Effector → Integration center
b) Receptor → Sensory neuron → Integration center → Motor neuron → Effector
c) Motor neuron → Receptor → Integration center → Sensory neuron
d) Effector → Sensory neuron → Receptor → Brain

A somatic reflex involves:
a) Skeletal muscle
b) Smooth muscle
c) Heart tissue
d) Glands

a) Correct – somatic reflexes act on voluntary muscles.
b) Wrong – autonomic reflex controls smooth.
c) Wrong – cardiac is autonomic.
d) Wrong – glandular is autonomic

An autonomic reflex involves:
a) Skeletal muscle
b) Smooth or cardiac muscle and glands
c) Joints only
d) Tendons only

a) Wrong – that’s somatic.
b) Correct – autonomic controls involuntary tissues.
c) Wrong – joints aren’t effectors.
d) Wrong – tendons aren’t target organs

The integration center of most reflexes is located in the:
a) Brainstem
b) Spinal cord
c) Cerebellum
d) Medulla oblongata

a) Wrong – higher reflexes only.
b) Correct – spinal cord handles simple reflex processing.
c) Wrong – cerebellum coordinates movement.
d) Wrong – medulla manages autonomic functions

Which trend is seen in the evolution of animal nervous systems?
a) Decrease in neuron number
b) Shift from nerve nets to centralized brains
c) Elimination of sensory organs
d) Loss of coordination ability

a) Wrong – neuron numbers increased.
b) Correct – nervous systems became centralized for complex behavior.
c) Wrong – sensory organs expanded.
d) Wrong – coordination improved

The vertebrate nervous system is divided into:
a) Brain and spinal nerves
b) Central and peripheral systems
c) Motor and sensory organs only
d) Reflex and hormonal networks

a) Wrong – incomplete.
b) Correct – CNS and PNS are the two main divisions.
c) Wrong – those are components

The central nervous system (CNS) includes:
a) Brain and spinal cord
b) Brain and cranial nerves
c) Spinal nerves and ganglia
d) Nerves and receptors

a) Correct – brain and spinal cord make up the CNS.
b) Wrong – cranial nerves are PNS.
c) Wrong – ganglia = PNS.
d) Wrong – receptors not part of CNS

The peripheral nervous system (PNS) includes:
a) Brain and spinal cord
b) Nerves and ganglia outside the CNS
c) Only cranial nerves
d) Only spinal nerves

a) Wrong – that’s CNS.
b) Correct – PNS links organs and limbs to CNS.
c) Wrong – includes spinal too.
d) Wrong – includes cranial as well

The somatic nervous system controls:
a) Involuntary organs
b) Skeletal muscle (voluntary movement)
c) Smooth muscle only
d) Hormone secretion

a) Wrong – that’s autonomic.
b) Correct – somatic enables conscious movement.
c) Wrong – smooth = autonomic.
d) Wrong – glands are endocrine

The autonomic nervous system (ANS) controls:
a) Skeletal muscle only
b) Voluntary functions
c) Involuntary internal organs and glands
d) Reflex arcs of the brain

a) Wrong – skeletal is somatic.
b) Wrong – autonomic is involuntary.
c) Correct – ANS regulates organs

The sympathetic division of the ANS:
a) Restores energy after stress
b) Increases heart rate and prepares for “fight or flight”
c) Slows breathing and digestion
d) Works only during sleep

a) Wrong – that’s parasympathetic.
b) Correct – sympathetic activates stress responses.
c) Wrong – it speeds these up.
d) Wrong – it’s active during alertness

The parasympathetic division of the ANS:
a) Stimulates fight or flight
b) Promotes “rest and digest” activities
c) Speeds up the heart
d) Increases adrenaline release

a) Wrong – that’s sympathetic.
b) Correct – parasympathetic calms the body and restores energy.
c) Wrong – it slows heart rate.
d) Wrong – adrenaline is sympathetic

The protective membranes covering the brain and spinal cord are called:
a) Myelin sheaths
b) Meninges
c) Nerves
d) Pia networks

a) Wrong – myelin covers axons.
b) Correct – meninges protect the CNS.
c) Wrong – nerves are PNS structures.
d) Wrong – “pia networks” is not a term

Arrange the meninges from outermost to innermost:
a) Pia → Arachnoid → Dura
b) Dura → Arachnoid → Pia
c) Arachnoid → Pia → Dura
d) Dura → Pia → Arachnoid

a) Wrong – reversed.
b) Correct – dura (outer)

The fluid that cushions and protects the brain is:
a) Synovial fluid
b) Blood plasma
c) Cerebrospinal fluid (CSF)
d) Lymph

a) Wrong – synovial cushions joints

The hindbrain includes:
a) Cerebrum and thalamus
b) Medulla oblongata

pons

The midbrain functions mainly as a:
a) Center for smell and taste
b) Relay for visual and auditory information and motor responses
c) Control of digestion
d) Storage for long-term memory

a) Wrong – smell and taste handled elsewhere.
b) Correct – midbrain integrates sensory input for reflexive movements.
c) Wrong – medulla controls digestion.
d) Wrong – memory is cerebrum

The forebrain includes:
a) Thalamus

hypothalamus

Which brain region regulates heart rate and breathing?
a) Cerebrum
b) Medulla oblongata
c) Thalamus
d) Cerebellum

a) Wrong – cerebrum handles thinking.
b) Correct – medulla controls vital autonomic functions.
c) Wrong – thalamus relays sensory input.
d) Wrong – cerebellum coordinates movement

The cerebellum controls:
a) Vision and hearing
b) Balance and coordination
c) Heart rate
d) Hormone secretion

a) Wrong – occipital and temporal lobes manage those.
b) Correct – cerebellum refines movement and posture.
c) Wrong – medulla does that.
d) Wrong – endocrine system does hormones

The thalamus functions as:
a) A relay center for sensory input to the cerebrum
b) The memory center of the brain
c) The primary motor cortex
d) The reflex integration center

a) Correct – thalamus routes sensory data to the cortex.
b) Wrong – hippocampus handles memory.
c) Wrong – motor cortex is cerebrum.
d) Wrong – reflexes use spinal cord

The hypothalamus regulates:
a) Muscle contraction only
b) Homeostasis

hunger

The cerebrum is responsible for:
a) Reflex actions
b) Conscious thought

learning

The spinal cord:
a) Produces digestive enzymes
b) Connects brain and PNS

coordinates reflexes
c) Stores red blood cells
d) Controls only voluntary actions

a) Wrong – digestion is in gut.
b) Correct – it relays information and manages reflex arcs.
c) Wrong – blood production occurs in bone marrow.
d) Wrong – includes involuntary reflexes

In vertebrates

which trend occurs in brain evolution?
a) Cerebrum size increases with behavioral complexity
b) Cerebellum shrinks
c) Forebrain disappears
d) Midbrain dominates all function

The gray matter of the spinal cord contains:
a) Myelinated axons
b) Neuron cell bodies and interneurons
c) White fibers only
d) Muscle fibers

a) Wrong – white matter has myelin.
b) Correct – gray matter holds neuron bodies for processing.
c) Wrong – that’s opposite.
d) Wrong – muscles aren’t in CNS

The white matter of the spinal cord contains:
a) Myelinated axons for signal transmission
b) Unmyelinated neurons
c) Cell bodies
d) Gray commissures

a) Correct – myelin gives white color and fast conduction.
b) Wrong – gray matter has those.
c) Wrong – found centrally

The brainstem includes which structures?
a) Medulla

pons

Which brain region expanded most through vertebrate evolution?
a) Medulla oblongata
b) Cerebrum
c) Midbrain
d) Cerebellum

a) Wrong – primitive structure.
b) Correct – cerebrum enlarged with intelligence and sensory processing.
c) Wrong – midbrain stayed small.
d) Wrong – cerebellum size stable

The musculoskeletal system provides:
a) Circulation and digestion
b) Support

movement

The three types of skeletal systems in animals are:
a) Endoskeleton

exoskeleton

A hydrostatic skeleton:
a) Uses fluid pressure for support and movement
b) Is composed of rigid bones
c) Is made of chitin plates
d) Is found only in vertebrates

a) Correct – muscles press on fluid-filled cavities to move body.
b) Wrong – that’s endoskeleton.
c) Wrong – that’s exoskeleton.
d) Wrong – mostly in invertebrates

An exoskeleton is:
a) A hard external covering made of chitin or calcium carbonate
b) An internal bone framework
c) A fluid cavity skeleton
d) A type of connective tissue

a) Correct – protects and supports body externally.
b) Wrong – that’s endoskeleton.
c) Wrong – that’s hydrostatic.
d) Wrong – not a tissue

The endoskeleton of vertebrates is composed primarily of:
a) Collagen only
b) Cartilage and bone
c) Chitin
d) Keratin

a) Wrong – collagen is a component but not the whole structure.
b) Correct – vertebrate skeletons combine flexible cartilage and rigid bone for support.
c) Wrong – chitin is in arthropod exoskeletons.
d) Wrong – keratin forms hair and nails

Osteocytes are:
a) Bone-forming cells
b) Mature bone cells that maintain bone tissue
c) Bone-destroying cells
d) Cells that make cartilage

a) Wrong – osteoblasts form new bone.
b) Correct – osteocytes are mature maintenance cells within lacunae.
c) Wrong – osteoclasts break down bone.
d) Wrong – chondrocytes make cartilage

Osteoblasts are responsible for:
a) Breaking down bone
b) Building new bone matrix
c) Making synovial fluid
d) Storing calcium in the muscle

a) Wrong – that’s osteoclast function.
b) Correct – osteoblasts secrete collagen and minerals to form bone.
c) Wrong – synovial fluid comes from joint membranes.
d) Wrong – muscle stores glycogen

Osteoclasts:
a) Build new bone
b) Resorb (break down) bone matrix
c) Secrete collagen
d) Make red blood cells

a) Wrong – osteoblasts build.
b) Correct – osteoclasts dissolve bone to release minerals.
c) Wrong – osteoblasts do that.
d) Wrong – blood cells form in marrow

Compact bone is:
a) Porous and filled with marrow spaces
b) Dense and forms the outer shaft of long bones
c) Found only in joints
d) Found only in cartilage plates

a) Wrong – that’s spongy bone.
b) Correct – compact bone is hard and solid for strength.
c) Wrong – bones exist throughout the body.
d) Wrong – cartilage is separate

Spongy bone:
a) Is completely solid
b) Contains trabeculae and red marrow spaces
c) Has no blood vessels
d) Exists only in the skull

a) Wrong – it has openings.
b) Correct – spongy bone houses marrow and lightens structure.
c) Wrong – it’s well vascularized.
d) Wrong – present in many bones

The functional unit of compact bone is the:
a) Sarcomere
b) Haversian system (osteon)
c) Myofibril
d) Trabecula

a) Wrong – sarcomere is in muscle.
b) Correct – osteons are cylindrical structures containing bone cells and canals.
c) Wrong – that’s muscle.
d) Wrong – trabecula is spongy bone element

The point where two bones meet is a:
a) Ligament
b) Joint (articulation)
c) Tendon
d) Muscle insertion

a) Wrong – connects bones.
b) Correct – a joint allows movement between bones.
c) Wrong – joins muscle to bone.
d) Wrong – that’s a muscle attachment site

Ligaments connect:
a) Muscle to bone
b) Bone to bone
c) Muscle to muscle
d) Cartilage to tendon

a) Wrong – tendons do that.
b) Correct – ligaments stabilize joints by linking bones.
c) Wrong – muscles attach via tendons.
d) Wrong – connective tissues don’t link like that

Tendons connect:
a) Bone to bone
b) Muscle to bone
c) Muscle to ligament
d) Bone to cartilage

a) Wrong – that’s ligament.
b) Correct – tendons anchor muscles to bones for movement.
c) Wrong – not their function.
d) Wrong – different connection

Cartilage is found:
a) In movable joints

nose

The three types of muscle are:
a) Skeletal

smooth

Skeletal muscle is:
a) Voluntary and striated
b) Involuntary and smooth
c) Found in the heart
d) Unstriated and voluntary

a) Correct – skeletal muscle has bands and is consciously controlled.
b) Wrong – describes smooth muscle.
c) Wrong – heart is cardiac.
d) Wrong – skeletal is striated

Cardiac muscle differs from skeletal muscle because it:
a) Lacks striations
b) Contains intercalated discs and is involuntary
c) Is voluntary
d) Is found in bones

a) Wrong – it’s striated.
b) Correct – discs allow electrical connection and automatic rhythm.
c) Wrong – it’s involuntary.
d) Wrong – not in bones

Smooth muscle is found in:
a) Bones
b) Walls of internal organs
c) Skin and tendons
d) Joints only

a) Wrong – bones are not muscular.
b) Correct – smooth muscle lines organs like stomach and vessels.
c) Wrong – those use skeletal support.
d) Wrong – joints lack muscle tissue

The smallest functional unit of muscle contraction is the:
a) Myofibril
b) Sarcomere
c) Actin filament
d) Muscle fiber

a) Wrong – myofibrils contain many sarcomeres.
b) Correct – sarcomeres shorten to create movement.
c) Wrong – actin is a component of sarcomere.
d) Wrong – fibers are bundles of sarcomeres

A myofibril is composed of repeating units called:
a) Sarcomeres
b) Actin fibers
c) Myosin molecules
d) Z-lines

a) Correct – myofibrils are chains of sarcomeres.
b) Wrong – actin is a thin filament within sarcomere.
c) Wrong – myosin is a protein component.
d) Wrong – Z-lines mark sarcomere boundaries

The two main filaments in muscle fibers are:
a) Troponin and tropomyosin
b) Actin (thin) and myosin (thick)
c) ATP and calcium
d) Collagen and keratin

a) Wrong – they’re regulatory proteins.
b) Correct – these sliding filaments cause contraction.
c) Wrong – energy and ions

The sliding-filament model states that:
a) Actin and myosin shorten
b) Filaments slide past each other to shorten the sarcomere
c) ATP stretches the myofibrils
d) Calcium causes muscle tearing

a) Wrong – filaments retain length.
b) Correct – cross-bridge cycling slides actin over myosin to contract.
c) Wrong – ATP powers cross-bridges not stretching.
d) Wrong – no tearing occurs

The neuromuscular junction (NMJ) is the site where:
a) Two muscles meet
b) A motor neuron communicates with a muscle fiber
c) Ligament attaches to muscle
d) Two bones connect

a) Wrong – muscles don’t connect directly to one another.
b) Correct – the NMJ is the synapse where a neuron’s signal triggers muscle contraction.
c) Wrong – ligaments connect bone to bone

The neurotransmitter released at the NMJ is:
a) Dopamine
b) Acetylcholine (ACh)
c) Serotonin
d) GABA

a) Wrong – dopamine regulates reward pathways.
b) Correct – ACh binds muscle receptors to initiate contraction.
c) Wrong – serotonin affects mood.
d) Wrong – GABA is inhibitory in the CNS

When ACh binds its receptor

which ion enters the muscle fiber?
a) Calcium
b) Potassium
c) Sodium
d) Chloride