Control and Coordination - Chapter 6 (Science)

A set of Question-and-Answer style flashcards covering nervous system, reflex actions, brain function, hormones in animals, plant coordination, and key concepts in control and coordination.

What are the two main types of plant movement described in section 6.2?

Growth-dependent movements caused by growth, and growth-independent movements not caused by growth.

Define reflex action.

A fast, automatic response to a stimulus that is usually involuntary and does not involve conscious thought.

What is a reflex arc and where is it formed?

A neural pathway that mediates a rapid reflex; it is formed in the spinal cord.

Describe the path of a nervous impulse in a neuron from reception to transmission.

Stimulus is detected by receptors at the dendrite; the impulse travels to the cell body, along the axon, and ends at the synapse where neurotransmitter is released to pass the signal to the next neuron.

What is a synapse?

A gap between two neurons where a chemical signal (neurotransmitter) crosses to transmit the impulse to the next neuron.

What is a neuromuscular junction?

The synapse between a motor neuron and a muscle cell, enabling nerve signals to trigger muscle contraction.

Name the three major regions of the brain and a general function of each.

Fore-brain (thinking and processing of sensory inputs), Mid-brain (coordination of signals and reflexes), Hind-brain (controls involuntary actions; cerebellum for movement precision; medulla for vital functions).

What is the peripheral nervous system?

Cranial nerves and spinal nerves that connect the brain and spinal cord to the rest of the body, enabling communication with muscles and glands.

How is the brain protected?

Inside the skull with cerebrospinal fluid for cushioning; the spinal cord is protected by the vertebral column.

How do nerve impulses cause muscle movement at the cellular level?

Nerve impulses trigger changes in the proteins inside muscle fibers, causing them to shorten and generate movement.

What is the difference between reflex actions and voluntary actions?

Reflex actions are rapid, involuntary responses often processed in the spinal cord; voluntary actions are conscious, decision-driven movements controlled by the brain.

What is phototropism in plants?

Directional growth of shoots toward light and roots away from light.

What is geotropism (gravitropism)?

Growth response to gravity: shoots grow upward and roots grow downward.

What are hydrotropism and chemotropism?

Growth toward water (hydrotropism) and growth toward chemicals (chemotropism), such as pollen tubes toward ovules.

What is auxin and how does it cause phototropic bending?

Auxin is produced at the shoot tip; it diffuses to the shaded side and stimulates cell elongation, causing the shoot to bend toward light.

What are cytokinins and gibberellins?

Cytokinins promote cell division; gibberellins promote stem growth and elongation; abscisic acid inhibits growth.

What is the role of iodine in hormone production?

Iodine is essential for the thyroid to make thyroxin, which regulates metabolism and growth; iodine deficiency can lead to goitre.

What is thyroxin and why is it important?

A thyroid hormone that regulates metabolism and growth; its synthesis requires iodine.

What is growth hormone and where is it produced?

A hormone secreted by the pituitary gland that regulates growth of the body; deficiency in childhood can cause dwarfism.

What hormones are involved in puberty and what do they do?

Testosterone in males and oestrogen in females drive the development of secondary sexual characteristics and reproductive development.

What is insulin and why is it important?

A hormone produced by the pancreas that regulates blood glucose levels; deficiency leads to diabetes.

What is adrenaline and what effects does it have on the body?

A hormone released by the adrenal glands during stress; increases heart rate, diverts blood to muscles, increases breathing, preparing the body for fight-or-flight.

What is the role of feedback mechanisms in hormone regulation?

Hormone release is regulated by feedback; for example, rising blood sugar triggers insulin release and falling sugar reduces insulin secretion.

How do the nervous and hormonal systems differ in control and coordination?

The nervous system uses rapid electrical impulses targeted to specific cells; the hormonal system uses chemical signals (hormones) that can affect many cells and act more slowly.

What is the role of the cerebellum?

Maintains posture and balance and ensures precision of voluntary movements.

What is the role of the medulla in the hind-brain?

Controls involuntary actions such as breathing and heart rate.

What is the role of receptors in our sense organs like taste and smell?

Receptors detect specific stimuli (gustatory for taste, olfactory for smell) and trigger nervous signals.

What is the role of hormones in plants and how do they diffuse?

Plant hormones like auxins, gibberellins, cytokinins, and abscisic acid coordinate growth, development, and environmental responses; they are synthesized away from their site of action and diffuse to the target area.

How do plants detect touch in the sensitive plant without nervous tissue?

They use electrical-chemical signaling between cells and changes in water content (turgor) to cause rapid leaf movement without muscle or nerve tissue.