Amazing human body & everyday biology

Question 1

Why does a bruise often change color while it heals?

Blood pigments trapped under the skin are gradually broken down.

Bones repeatedly change color underneath The lungs send different colors to the injury The skin is changing into different materials Hemoglobin and related pigments are chemically broken down over time

Question 2

Why is the skull important?

It forms a hard protective structure around a delicate organ.

It provides mechanical protection for the brain It produces all thoughts It absorbs nutrients from food It pumps blood into the body

Question 3

What is synovial fluid used for in many movable joints?

Think of biological lubrication.

Producing nerve impulses Transporting oxygen to the lungs Lubricating the joint and supporting cartilage Digesting proteins

Question 4

Why is urine often darker yellow when a person is dehydrated?

The body tries to conserve something when fluid intake is low.

The lungs add food coloring to it The bladder produces extra blood Bones release yellow pigment into urine The kidneys conserve water, making urine more concentrated

Question 5

Why do some people get 'pins and needles' after sitting awkwardly for a while?

Temporary pressure can affect nerves.

Tiny pins physically form under the skin Pressure can temporarily disturb nerve signaling and local circulation Bones release electricity into the skin Blood permanently stops flowing

Question 6

Why is oxygen essential for most cells in the human body?

It is used in mitochondria to extract energy efficiently from nutrients.

It prevents cells from using energy It enables efficient ATP production through aerobic cellular respiration It is converted directly into bones It replaces DNA

Question 7

What is homeostasis?

Your body constantly adjusts conditions such as temperature, water balance and blood glucose.

The regulation of internal conditions within workable ranges The process of growing hair only The movement of bones during walking The digestion of one specific food

Question 8

Why do fingertips have a strong sense of touch?

They contain many sensory receptors packed into a relatively small area.

They have a high density of touch-sensitive nerve endings Fingertips contain more bones than the rest of the body Blood itself detects objects Fingertips contain tiny eyes

Question 9

What protein makes up much of human hair and nails?

It is a tough structural protein.

Hemoglobin Insulin Keratin Amylase

Question 10

What pigment contributes strongly to the color of human skin, hair and eyes?

It also helps absorb ultraviolet radiation in the skin.

Adrenaline Insulin Keratinase Melanin

Question 11

Why can muscles feel tired after intense exercise?

Working muscle fibers undergo temporary changes when activity is demanding.

The muscles permanently stop receiving blood Temporary metabolic and nervous-system changes reduce their ability to generate force Bones temporarily replace the muscles All muscle cells die during exercise

Question 12

What is one important job of saliva when you eat?

Digestion begins before food reaches your stomach.

It stores oxygen It pumps blood around the body It moistens food and begins breaking down some starch It produces red blood cells

Question 13

Why might you quickly pull your hand away after touching something painfully hot?

The nervous system can trigger a protective response very rapidly.

A withdrawal reflex activates muscles to move the hand away Your kidneys move the arm Your bones detect the color of the object Your stomach pushes your hand backward

Question 14

What are capillaries?

They are the smallest blood vessels and have very thin walls.

Nerve cells in the brain Tiny bones in the fingers Air sacs in the lungs Tiny blood vessels where many substances are exchanged with tissues

Question 15

Why can loud sounds potentially damage hearing?

Delicate sensory hair cells in the inner ear can be injured.

Intense sound can damage sensory hair cells involved in hearing The ear stops containing bones after loud sounds Sound turns into blood inside the ear Loud sound dissolves the outer ear