Biology Chapter on Hormones and Homeostasis

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Questions and Answers

What is the role of the sensory neuron in the reflex action process?

To connect the muscle to the brain

To receive stimuli from the environment

To send electrical impulses to the spinal cord (correct)

To release neurotransmitters

Which of the following statements best describes synapses?

They allow impulses to travel in both directions.

They only transmit neurochemical signals.

They are chemical gaps that connect neurons. (correct)

They are physical junctions where neurons touch.

What occurs after neurotransmitters bind to the postsynaptic membrane?

They cause the postsynaptic neuron to generate an electrical impulse. (correct)

They initiate muscle contraction.

They trigger impulse generation in the presynaptic neuron.

They travel back to the presynaptic neuron.

What is one primary function of synapses in the nervous system?

Ensuring impulses travel in only one direction Signup and view all the answers

Once neurotransmitters have served their purpose, what happens to them?

They are destroyed to prevent continued stimulation. Signup and view all the answers

Reflex actions are characterized by which of the following traits?

They are automatic and fast. Signup and view all the answers

What is the role of the motor neuron in a reflex action?

To carry impulses to the muscle to initiate a response. Signup and view all the answers

What do we call the chemical messengers released by the presynaptic neuron at the synapse?

Neurotransmitters Signup and view all the answers

What does respiration in living organisms primarily involve?

Chemical reactions releasing energy Signup and view all the answers

Which of the following is NOT one of the MRS GREN characteristics of life?

Structure Signup and view all the answers

What is the purpose of excretion in organisms?

To remove toxic waste and excess substances Signup and view all the answers

What does a species represent in biological classification?

A group of organisms that produce fertile offspring Signup and view all the answers

In the binomial system of classification, what is the correct format for naming an organism?

First part is capitalized, second part is lowercase Signup and view all the answers

What essential materials do plants need for nutrition?

Light, carbon dioxide, and nutrients Signup and view all the answers

How were organisms first classified, according to the binomial system?

By dividing them into smaller specialized groups Signup and view all the answers

What characteristic involves organisms increasing in size and cell number?

Growth and development Signup and view all the answers

What is the term used to describe a plant's growth response towards a stimulus?

Tropism Signup and view all the answers

In which direction do shoots exhibit a positive response according to gravitropism?

Upwards Signup and view all the answers

What will happen to seedlings in setup B when exposed to equal light from all sides?

They will grow straight upwards without curving Signup and view all the answers

Which plant response is characterized by roots growing downwards towards gravity?

Positive gravitropic response Signup and view all the answers

What condition causes seedlings to exhibit yellowing leaves and a slender appearance in investigation C?

Insufficient light exposure Signup and view all the answers

What is the primary function of the iris muscles in relation to light?

To control the amount of light entering the eye Signup and view all the answers

During eye accommodation, what happens when focusing on a close object?

The ciliary muscles contract and the suspensory ligaments loosen Signup and view all the answers

What is the role of the rod cells in the retina?

They can detect light at low levels for night vision Signup and view all the answers

What occurs in the pupil reflex when exposed to bright light?

The circular muscles contract while the radial muscles relax Signup and view all the answers

How do the circular and radial iris muscles function?

They are antagonistic and work against each other. Signup and view all the answers

What is the significance of the fovea in the eye?

It is where light is focused for sharp, colored images. Signup and view all the answers

What happens to the light receptors in the eye during low light conditions?

They activate the radial muscles to contract, dilating the pupil. Signup and view all the answers

Which type of receptor cells are concentrated in the fovea?

Cone cells for color vision Signup and view all the answers

What is the role of the motor neuron in the response pathway?

To carry the impulse to the effector (muscle or gland) Signup and view all the answers

What is the primary purpose of accommodation in the eye?

To allow the eye to focus on objects at varying distances Signup and view all the answers

What is the primary role of insulin in maintaining homeostasis?

To convert excess glucose into glycogen Signup and view all the answers

Which of the following is NOT a function of adrenaline during a fight or flight response?

Diverting blood flow towards non-essential organs Signup and view all the answers

What happens during vasoconstriction?

Blood vessels leading to the skin capillaries narrow Signup and view all the answers

In Type 1 diabetes, what consequence arises from the lack of insulin production?

Blood glucose levels often become excessively high Signup and view all the answers

How does the human body primarily maintain its internal temperature?

Through nerve impulses from the brain to skin effectors Signup and view all the answers

What is a consequence of high body temperature exceeding 37°C?

Enzymes can denature and lose effectiveness Signup and view all the answers

What mechanism controls the adverse effects of rising and falling levels of blood glucose?

Negative feedback Signup and view all the answers

Which of the following statements about adrenaline is false?

Decreases pulse rate during physical stress Signup and view all the answers

How does glycogen function in glucose regulation?

It is stored in the muscles and liver to regulate blood sugar levels Signup and view all the answers

What is the defining characteristic of homeostasis?

Maintenance of a fixed internal environment Signup and view all the answers

What is NOT a symptom of Type 1 diabetes?

Increased muscle gain Signup and view all the answers

What physiological change occurs when the body is cold?

Vasoconstriction to reduce blood flow to the skin Signup and view all the answers

Which of the following correctly describes negative feedback?

Works to maintain conditions within a narrow range Signup and view all the answers

What happens to glucose levels in the blood after eating a meal?

They usually increase and require insulin for regulation Signup and view all the answers

Why is maintaining a temperature of around 37°C crucial for the human body?

To ensure enzymes function optimally Signup and view all the answers

Study Notes

Adrenaline

Increases blood glucose concentration to increase respiration in muscle cells.
Increases pulse rate and breathing rate to deliver glucose and oxygen to, and remove carbon dioxide from, muscle cells more quickly.
Diverts blood flow towards muscles and away from non-essential parts of the body, such as the alimentary canal, to ensure reactants of respiration are available.
Dilates pupils to allow more light to reach the retina, so more information can be sent to the brain.

Homeostasis

Maintenance of a constant internal environment.
Internal conditions (temperature, blood pressure, water concentration, glucose concentration etc.) need to be kept within set limits.
If conditions deviate far from the norm, the body will not function properly.

Insulin

Secreted into the blood when blood glucose levels are high, usually after a meal.
Helps to prevent glucose from being lost in the urine.
Converts excess glucose into glycogen in the liver and muscles.
Decreases blood glucose concentration.
Glycogen can be converted back to glucose when blood glucose levels are low.

Negative Feedback

Occurs when conditions change from the ideal or set point.
If the level of something rises, control systems are switched on to reduce it again.
If the level of something falls, control systems are switched on to raise it again.

Type 1 Diabetes

Blood glucose levels cannot be regulated because the insulin-secreting cells in the pancreas do not produce insulin.
Blood glucose levels are often too high.
Treated by injecting insulin.
Symptoms include extreme thirst, weakness or tiredness, blurred vision, weight loss, and loss of consciousness in extreme cases.
People with Type 1 diabetes need to monitor their blood glucose levels throughout the day.
Can help to control blood glucose levels by being careful with their diet and exercising.

The Skin & Homeostasis

Control of body temperature is a homeostatic mechanism.
The human body maintains a temperature of 37°C, the optimum temperature for enzyme activity.
Fatty tissue under the dermis acts as a layer of insulation.

Vasoconstriction & Vasodilation

When cold, blood flow in capillaries slows down (vasoconstriction), reducing heat loss.
When hot, blood flow in capillaries increases (vasodilation), allowing more heat loss through the skin surface.

Gravitropism & Phototropism

Plants respond to changes in the environment for survival.
Shoots grow upwards and towards light (positive phototropic response, negative gravitropic response).
Roots grow downwards and towards gravity (negative phototropic response, positive gravitropic response).

The Binomial System

Organisms are classified using a hierarchical system.
The binomial system is used for naming organisms. It is made up of two parts, the genus (always given a capital letter) and the species (starting with a lowercase letter).

Reflex Actions

Automatic, fast, protective.
Example: The withdrawal reflex (removing a hand from a hot object).

Synapses

Junctions between neurons.
Electrical impulses are transmitted across synapses.

Sense Organs as Receptors

Receptors are groups of specialised cells.
Sense organs contain groups of receptors that respond to specific stimuli.

Eye Structure

The eye is a sense organ sensitive to light.
Key structures include the cornea, iris, lens, retina, and optic nerve.

The Pupil Reflex

Controls the amount of light that enters the eye.
The pupil dilates in dim light and constricts in bright light.

Iris Muscles

The pupil reﬂex occurs due to changes in the iris muscles.
The iris contains circular muscles and radial muscles.
The circular and radial muscles of the iris are antagonistic.

Eye Accommodation

The way in which the eye focuses on near or distant objects.
The shape of the lens is changed, brought about by contraction or relaxation of the ciliary muscles and adjustment of tension in the suspensory ligaments.

Rods & Cones

Rod cells are located all over the retina and allow us to see in dim light.
Cone cells are concentrated in the fovea and are responsible for color vision.

Hormones & Their Associated Glands

Hormones are chemical messengers produced by endocrine glands.
They are transported in the bloodstream to target cells.
They regulate a variety of functions, including growth, metabolism, and reproduction.

Plant Responses to Stimuli

Plants respond to stimuli such as light, water and gravity.
Responses are often slower than animals.
Growth towards a stimulus is known as a positive response, while growth away from a stimulus is known as a negative response.
Responses are known as tropisms.

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Description

This quiz explores key concepts regarding adrenaline, homeostasis, and insulin. Test your knowledge on how these hormones affect bodily functions and maintain internal equilibrium. Understand the physiological responses triggered by these critical hormones in relation to metabolism and blood regulation.