Biology: Homeostasis, Nutrition, Plant Transport, and Animal Movement

What is homeostasis?

The maintenance of stable internal conditions in the body, including oxygen, carbon dioxide, nutrient, and waste levels.

What does the respiratory system do?

Brings oxygen into the body and removes carbon dioxide.

What does the circulatory system do?

Transports oxygen, nutrients, carbon dioxide, and wastes in the blood.

What does the digestive system do?

Breaks down food and absorbs nutrients into the bloodstream.

What does the urinary/excretory system do?

Filters blood and removes wastes through urine.

What does the muscular system do?

Uses oxygen and nutrients to make ATP and produces carbon dioxide and other wastes.

Where does oxygen enter the body?

Through the nose or mouth.

What pathway does oxygen follow through the body?

Nose or mouth → trachea → lungs → alveoli → capillaries → heart and blood vessels → body tissues and cells.

Where does oxygen move from the lungs into the blood?

From the alveoli into nearby capillaries.

Where is carbon dioxide produced?

In body cells during cellular respiration.

What pathway does carbon dioxide follow out of the body?

Body cells → bloodstream → lungs → alveoli → exhaled.

How does carbon dioxide leave the blood?

It diffuses from the blood into the alveoli and is exhaled.

How are nutrients transported to body cells?

Food is broken down by the digestive system, nutrients are absorbed primarily through the small intestine, enter the bloodstream, and are transported to body cells.

Where are most nutrients absorbed?

The small intestine.

How are metabolic wastes removed from the body?

Wastes enter the bloodstream, the kidneys filter them from the blood, and they leave the body in urine.

What happens to breathing rate when you exercise?

It increases to bring in more oxygen and remove more carbon dioxide.

What happens to heart rate and blood flow during exercise?

Both increase to deliver oxygen and nutrients to working muscles faster.

What happens to muscle cells during exercise?

They use more oxygen and glucose to produce ATP.

Why does carbon dioxide production increase during exercise?

Working muscles produce more carbon dioxide during increased cellular activity.

What is an autotroph?

An organism that makes its own organic food using light energy or chemical energy.

What is a heterotroph?

An organism that obtains energy by consuming or absorbing organic matter from other organisms.

What does the word auto mean in autotroph?

Self; an autotroph makes its own food.

What does the word hetero mean in heterotroph?

Other; a heterotroph gets food from another source.

What is the typical nutrition mode of plants?

Primarily autotrophs; they make sugars through photosynthesis.

What is the nutrition mode of animals?

Heterotrophs; they consume other organisms or organic material.

What are the two nutrition modes of bacteria?

Both; some make their own food while others obtain food from their environment.

What are the two nutrition modes of protists?

Both; some photosynthesize while others consume or absorb food.

How do fungi obtain nutrients?

They are heterotrophs that absorb nutrients from living or dead organic matter.

What are the two vascular tissues in plants?

Xylem and phloem.

What does xylem transport?

Water and dissolved minerals.

What does phloem transport?

Sugars, mainly sucrose.

What direction does water move through xylem?

Primarily upward from roots to leaves.

What direction does sugar move through phloem?

From source to sink; direction depends on the locations of the source and sink.

What causes water to move upward through xylem?

Transpiration creates tension that pulls water upward.

What is transpiration?

The evaporation of water from leaf surfaces.

What helps keep the water column together in xylem?

Cohesion between water molecules.

How is sugar transported through phloem?

ATP helps load sugars into phloem, water enters by osmosis, and pressure differences push sugar-containing fluid from source to sink.

What is a source in phloem transport?

A location where sugars are produced, often the leaves.

What is a sink in phloem transport?

A location where sugars are used or stored, such as roots, fruits, and growing tissues.

What role does ATP play in phloem transport?

ATP helps load and unload sugars.

What causes pressure to increase in phloem?

Water enters the phloem by osmosis after sugars are loaded.

What is the main difference between xylem and phloem movement?

Xylem water is pulled upward by transpiration, while phloem sugar is pushed from source to sink by pressure differences.

What are the four forces acting on a moving animal?

Thrust, drag, lift, and weight (gravity).

What is thrust?

The force that propels an animal forward.

What is drag?

Resistance from air or water that opposes movement.

What is lift?

An upward force generated by airflow around a wing that helps support an animal in flight.

What is weight?

The downward force caused by gravity.

What force must be counteracted during flight?

Weight (gravity).

What adaptation helps animals fly?

Wings generate lift, while lightweight bones and a streamlined body can also help.

What force is especially important during swimming?

Drag (water resistance).

What adaptation reduces drag during swimming?

A streamlined body reduces resistance as an animal moves through water.

What adaptations help fish generate thrust?

Fins and a powerful tail.

What is the relationship between lift and weight during flight?

Lift helps counteract weight (gravity).

What is the relationship between streamlined bodies and drag?

A streamlined body reduces drag and resistance.

Why is surface area important for organisms?

Increasing surface area provides more area over which to absorb or exchange materials.

What are root hairs?

Tiny, thin extensions of root cells that greatly increase the root's surface area.

What is the function of root hairs?

They increase the amount of water and minerals a plant can absorb from the soil.

What are villi?

Fingerlike projections in the small intestine that increase surface area.

What are microvilli?

Microscopic projections on cells lining the villi that further increase surface area.

What is the function of villi and microvilli?

They increase surface area, allowing nutrients to be absorbed into the bloodstream more efficiently.

What is another animal example of increased surface area?

Alveoli in the lungs or fish gills.

What is the main benefit of increased surface area?

More opportunity for exchange or absorption.

What does form follows function mean?

A structure's physical design helps it perform its job.

What are alveoli?

Tiny, balloon-like air sacs in the lungs.

What is the function of alveoli?

Oxygen diffuses from the air in the alveoli into the blood, while carbon dioxide diffuses from the blood into the alveoli to be exhaled.

What structural features make alveoli effective?

Millions of alveoli provide a large surface area; their walls are extremely thin and moist.

What are capillaries?

Extremely small blood vessels with walls about one cell thick.

What is the function of capillaries surrounding alveoli?

They bring blood close to the air in the alveoli, allowing oxygen and carbon dioxide to diffuse between air and blood.

Why do alveoli and capillaries have thin walls?

Thin walls shorten the distance gases must diffuse, allowing rapid gas exchange.

Why do alveoli have a large surface area?

It allows more gas exchange to occur at once.

Why are alveolar surfaces moist?

Moist surfaces allow gases to dissolve before diffusing.

Why is there a dense capillary network around alveoli?

It brings blood close to the alveoli and supports ongoing gas exchange.

How does oxygen move from the alveoli into the body?

Oxygen diffuses across the thin alveolar and capillary walls into the blood, and red blood cells carry it throughout the body.

What are the three main sensory receptor types?

Chemoreceptors, mechanoreceptors, and photoreceptors.

What do chemoreceptors detect?

Chemicals; examples include taste and smell.

What do mechanoreceptors detect?

Physical pressure, movement, vibration, and sound; examples include touch and hearing.

What do photoreceptors detect?

Light; an example is vision.

How does the brain distinguish between different types of stimuli?

By identifying which sensory neurons and pathways are activated.

What determines whether a sensation is interpreted as taste or smell?

The sensory neurons and pathways activated; taste pathways are interpreted as taste and smell pathways as smell.

How is stimulus intensity communicated by the nervous system?

Through the frequency of action potentials.

What happens to action-potential frequency when a stimulus gets stronger?

Action potentials generally occur more frequently.

What happens to action-potential frequency when a stimulus gets weaker?

Action potentials occur less frequently per unit of time.

How does a loud sound differ from a quiet sound in action-potential frequency?

A loud sound generally produces a higher firing rate than a quiet sound.

What is the key difference between stimulus type and stimulus intensity?

Different pathways communicate the type of sensation, while action-potential frequency communicates intensity.