science & technology Online Quiz - 309

Aluminum is the correct answer - the majority of traditional aircraft structures are built from aluminum alloys due to their excellent strength-to-weight ratio and corrosion resistance. While modern aircraft increasingly use carbon fiber composites, aluminum remains the primary material for most commercial aircraft. Steel is too heavy for primary airframe structure.

Lift & Drag is the correct answer - both forces are essential for flight. Lift opposes gravity and keeps the aircraft airborne, generated primarily by the wings. Drag opposes forward motion and is actually necessary during landing - flaps and other devices increase drag to slow the aircraft. During takeoff, lift must exceed weight while drag must be overcome by engine thrust. Pressure differences create these forces but isn't itself the aerodynamic force.

Airbus is the correct answer - it's the largest European aircraft manufacturer and one of only two major commercial aircraft manufacturers globally alongside Boeing. Headquartered in France/with operations across Europe, Airbus produces the A320 family, A330, A350, and A380. Embraer is Brazilian, Saab is Swedish (mostly military), and Alenia is Italian.

Carbon Composites is the correct answer - carbon fiber reinforced polymer (CFRP) composites represent the latest advancement in aircraft construction, offering superior strength-to-weight ratio compared to aluminum. Modern aircraft like the Boeing 787 Dreamliner and Airbus A350 use extensive carbon composite structures. Titanium is also used but primarily for specific high-stress components like landing gear and engine parts.

Airbus A380 is the correct answer - it's the world's largest passenger airliner by capacity, carrying up to 853 passengers in a typical configuration. The double-deck, four-engine A380 was in production from 2007-2021. The Boeing 747 is smaller but was the previous largest. The A340 is a smaller Airbus wide-body, and Gripen is a fighter jet.

Modern commercial and military aircraft primarily use gas turbine engines, including turbofans, turbojets, turboprops, and turboshafts. Gas turbines offer superior power-to-weight ratio, fuel efficiency at high altitudes, and reliability compared to piston engines. Piston engines are largely confined to small general aviation aircraft today.

The lungs are situated in the thoracic cavity, which is the chamber of the body located above the diaphragm. The thoracic cavity is bounded by the rib cage and contains the lungs, heart, and other organs. The abdominal cavity contains digestive organs, pericardial cavity surrounds the heart, and buccal cavity is the mouth cavity.

Human somatic cells contain 46 chromosomes, organized as 23 pairs - one set from each parent. This includes 44 autosomes and 2 sex chromosomes (XX or XY). The 23 chromosome count refers only to the chromosome types in a haploid set (gametes), not the total in body cells.

Enzymes are biological catalysts that speed up chemical reactions in the body. They are most prominently involved in digestion, where they break down complex food molecules into simpler, absorbable nutrients in the digestive tract.

While digestion begins in the stomach through acid and enzyme action, the majority of digestion and nearly all nutrient absorption occurs in the small intestines. The small intestines have a huge surface area with villi and microvilli to maximize absorption.

The tibia, also called the shinbone, is the larger and stronger of the two bones in the lower leg (the other being the fibula). It connects the knee to the ankle and bears most of the body's weight.

Hemoglobin contains iron ions (Fe²⁺) in its heme groups, which bind to oxygen molecules in the lungs and release them in tissues. Each hemoglobin molecule can carry up to 4 oxygen molecules thanks to its 4 iron-containing heme groups.

Red blood cells (erythrocytes) are produced in the bone marrow through a process called erythropoiesis. In adults, this primarily occurs in the vertebrae, sternum, ribs, and pelvis. The liver produces RBCs only during fetal development.

The cerebrum is the largest part of the human brain, making up about 85% of its weight. It's responsible for higher functions like thought, memory, reasoning, and voluntary movement. The cerebellum coordinates movement, while the medulla controls vital functions like breathing and heart rate.

Calcium phosphate (specifically hydroxyapatite) is the primary mineral component of bones and teeth, providing hardness and strength. Bones are about 60-70% mineral (mostly calcium phosphate) and 30-40% organic matrix (mostly collagen).