Biology and Human Systems Overview

Comprehensive practice flashcards covering basic biology, including cell transport, human circulatory system, plant transport, and the nervous system based on lecture notes.

What is diffusion?

Diffusion is the movement of particles from a region of high concentration to a region of low concentration until equilibrium.

What are three examples of diffusion provided in the notes?

1. The smell of perfume; 2. Gas exchange; 3. Dipping a tea bag into water.

What does it mean to move down the concentration gradient?

The movement of particles from high to low concentration.

Define osmosis.

Osmosis is the movement of water molecules from a region of high concentration to a region of low concentration through a selective semi-permeable membrane.

What are the three types of solutions that facilitate osmosis?

1. Hypotonic; 2. Hypertonic; 3. Isotonic.

What occurs in a hypotonic solution?

A solution with a lower solute concentration than the cell causes water to move into the cell.

What occurs in a hypertonic solution?

A solution with a higher solute concentration than the cell causes water to move out of the cell.

What is an isotonic solution?

A solution that has the same solute concentration, resulting in no net movement of water across the cell membrane.

What happens to an animal cell versus a plant cell in a hypotonic solution?

An animal cell becomes lysed (bursts), while a plant cell becomes turgid (swells).

What happens to an animal cell versus a plant cell in a hypertonic solution?

An animal cell becomes shrivelled (shrinks), while a plant cell becomes flaccid (plasmolysed/soft).

What is passive transport?

The movement of substances across a cell membrane from high to low concentration without using energy ($ATP$).

What is active transport?

The movement of substances across a cell membrane from low to high concentration using energy ($ATP$).

What are the three main components of the Human Circulatory System?

The blood, the blood vessel, and the heart.

What are the three primary functions of blood?

1. Transports substances such as oxygen and hormones; 2. Distributes heat to maintain constant body temperature; 3. Helps defend the body against disease.

What is the composition of plasma?

Mostly water with dissolved substances such as hormones, glucose, salts, antibodies, and amino acids.

Describe the structure of red blood cells (erythrocytes).

They are biconcave in shape, have no nucleus, contain a red pigment called haemoglobin, and are elastic to squeeze into small spaces.

How is oxyhaemoglobin formed?

Oxygen combines with haemoglobin in the red blood cells.

What is the function of Lymphocytes?

They produce antibodies and antitoxins to destroy pathogens.

How do Phagocytes move and what is their function?

They move by pseudopodia (false foot) and their function is to engulf and destroy pathogens.

What are platelets and what is their lifespan?

Platelets are cell fragments formed in the red bone marrow that help blood to clot and live for about $10$ days.

Compare the thickness of artery walls and vein walls.

Arteries have thick outer walls and thick inner layers of muscle and elastic; veins have thin outer walls and thin inner layers of muscle and elastic fibers.

What is the function of valves in veins?

Values prevent the backflow of blood, trapping it if it tries to flow backwards.

Why are capillary walls very thin (single layer of cells)?

To allow substance exchange, such as gaseous exchange, between blood and body cells via diffusion.

What is the function of the Left ventricle?

This chamber receives oxygenated blood from the left atrium and pumps it through the aorta to the rest of the body.

What is the function of the Vena cava?

It receives deoxygenated blood from the body and transports it to the right atrium.

Why does the left ventricle have thicker walls than the right ventricle?

Because it must pump blood over a longer distance to the whole body.

Define transpiration.

Transpiration is the loss of water vapor from the leaves of a plant through the stomata.

How does high humidity affect transpiration?

Transpiration decreases because humidity reduces the concentration gradient.

Contrast the status of Xylem and Phloem cells.

Xylem consists of dead cells strengthened with lignin; Phloem cells are alive and have organelles in the companion cells.

What happens when guard cells gain water?

They become turgid and the stomata open.

What are the results of a ringing experiment?

Water transport continues (xylem intact), but sugar cannot move past the ring; roots eventually die, leading to the death of the whole plant.

What are the functions of the Cerebrum, Cerebellum, and Medulla oblongata?

Cerebrum: Thinking, memory, and voluntary actions. Cerebellum: Balance and muscle coordination. Medulla oblongata: Controls involuntary actions like breathing.

What consists of the Peripheral Nervous System (PNS)?

Cranial nerves and spinal nerves.

Define a Reflex arc.

A rapid automatic, involuntary response to a stimulus without conscious thought, protecting the body from injury.

What is the pathway of a reflex action?

Stimulus $\rightarrow$ Receptor $\rightarrow$ Sensory neuron $\rightarrow$ Relay neuron (spinal cord) $\rightarrow$ Motor neuron $\rightarrow$ Effector $\rightarrow$ Response.

Name the fatty insulating layer of a neuron and its function.

The Myelin sheath; it speeds up nerve impulse transmission.

What is the function of the Cornea?

It refracts (bends) light entering the eye.

Define Myopia and how it is corrected.

Myopia (Short-sightedness) is when near objects are seen clearly but the eyeball is too long, causing images to form in front of the retina; it is corrected with a concave lens.

Define Hyperopia and how it is corrected.

Hyperopia (Long-sightedness) is when distant objects are seen clearly but the eyeball is too short, causing images to form behind the retina; it is corrected with a convex lens.