Cell Structure and Function Quiz

Cell Structure and Function

• Nucleolus: Produces ribosomes and RNA.
• Cell Wall: Provides rigidity and protection to the cell.
• Chloroplasts: Site of photosynthesis, containing chlorophyll.
• Plasmodesmata: Channels through the cell wall that allow transport between cells.
• Amyoplasts: Store starch and convert it to glucose for energy.
• Vacuole: Stores water and chemicals; maintains cell turgor.
• Tonoplast: The membrane surrounding the vacuole; controls water flow and protects it.
• Gram-positive bacteria: More susceptible to antibiotics due to a permeable cell wall, unlike gram-negative bacteria with a semi-permeable wall.

Plant Cell Adaptations

• Palisade cells: Closely packed for a continuous light-absorbing layer. Contain chloroplasts for photosynthesis and a large vacuole to maintain turgor.

• Root hair cells: Have an elongated root hair to increase surface area for water absorption. Large vacuoles with low water potential draw water into the cell. Thin cell walls facilitate osmosis and diffusion.

Animal Cell Adaptations

• Sperm cells: Contain many mitochondria for energy, a head with an acrosome (enzyme-containing) for egg penetration, a haploid nucleus (half the genetic material), and a tail (undulipodium) for movement.
• Egg cells: Contain a haploid nucleus, a protective layer (zona pellucida) to prevent multiple sperm entry and the corona radiata for development.
• Red blood cells: Lack a nucleus for increased oxygen-carrying capacity, have a biconcave shape for a larger surface area for gas exchange, contain hemoglobin to bind oxygen, and are flexible to pass through capillaries.
• White blood cells: Possess a multi-lobed nucleus for squeezing through tissues and lysosomes containing enzymes to digest pathogens.

Epithelial Tissue

• Squamous epithelium: A single layer of flat cells, lining surfaces like alveoli. Smoking damages it by causing inflammation, scarring, and thickening, increasing the diffusion pathway.
• Columnar epithelium: Column-shaped with ciliated cells (cilia sweep away pathogens) and goblet cells (produce mucus). Smoking damages cilia, hindering mucus removal.
• Endothelial tissue: Lines blood vessels, lymphatic vessels, and the heart; is a single layer of flattened cells. Atherosclerosis involves white blood cells depositing fatty substances (cholesterol) beneath the lining, potentially causing angina, mini-strokes, heart attacks, and aneurysms.

Muscle Tissue

• Skeletal muscle: Attached to bones; voluntary control.
• Cardiac muscle: In the heart; involuntary control.
• Smooth muscle: In the walls of hollow organs; involuntary control.
• Muscle fiber structure: Ordered components (muscle -> bundle of fibres -> fibre -> myofibril -> filaments) filled with organelles like mitochondria, nuclei, and specialised ER.
• Muscle Contraction: Sarcomere shortens.

Nervous System

• Neurone (nerve cell): Contains dendrites (receive impulses), soma (cell body), nucleus, axon (sends impulses), myelin sheath (insulation), Schwann cells (form myelin), nodes of Ranvier (gaps in myelin), and axon terminals (transmit impulses to the next cell).
• Myelinated vs. non-myelinated: Myelinated neurones conduct impulses faster due to the saltatory conduction (jumping between nodes of Ranvier).
• Resting potential: Neurone at -70mV, polarized with K+/Na+ pump working.
• Action potential: Impulse passing along axon at +35mV.

Muscle Fiber Types

• Slow-twitch: Aerobic exercise; slower contraction but more endurance, more mitochondria, myoglobin, and capillaries.
• Fast-twitch oxidative: Mid-range sports, quick contraction with endurance.
• Fast-twitch glycolytic: Sprinting; quick contraction but limited endurance; less mitochondria and capillaries, high glycogen.

COPD (Chronic Obstructive Pulmonary Disorder)

• Caused by emphysema, bronchitis, and asthma.
• Symptoms include breathlessness, persistent coughing, and phlegm build-up.