Biology Class: Signalling Molecules and Circulation

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Questions and Answers

Which of the following is NOT a method of chemical transmission for signalling molecules?

Endocrine

Paracrine

Transmembrane (correct)

Autocrine

What characterizes hydrophobic signalling molecules?

They usually bind to intracellular receptors. (correct)

They are generally soluble in water.

They do not easily penetrate the cell membrane.

They typically act on cells at a distance.

In the stimulus-response model, what is the primary role of signal transduction?

To amplify and convey the signal within the cell. (correct)

To maintain cellular homeostasis.

To detect the external stimuli.

To release signalling molecules into the bloodstream.

Which of these pathways is classified as an extrinsic pathway of apoptosis?

Fas ligand pathway Signup and view all the answers

What is a distinguishing feature of neurotransmitters compared to hormones?

Neurotransmitters typically act locally and quickly. Signup and view all the answers

Which statement about cytokinins is accurate?

They play a key role in plant cell division. Signup and view all the answers

Apoptosis can occur through which of the following mechanisms?

Both intrinsic and extrinsic pathways Signup and view all the answers

What function do arteries serve in the circulatory system?

They carry blood away from the heart. Signup and view all the answers

What is the primary site for the exchange of materials in the circulatory system?

Capillaries Signup and view all the answers

Why can't gases and materials pass through arteries and veins?

They have thick walls. Signup and view all the answers

How do substances diffuse between capillaries and cells?

From interstitial fluid to/from cells. Signup and view all the answers

What prevents the flow of fluid in lymph vessels?

They have closed ends. Signup and view all the answers

What characteristic of capillaries allows them to be effective in material exchange?

They have a single layer of cells. Signup and view all the answers

Which statement correctly describes capillary networks?

They provide access to almost every cell in the body. Signup and view all the answers

What role does interstitial fluid play in the exchange process?

It facilitates diffusion between cells and capillaries. Signup and view all the answers

What is the primary function of tight junctions in animal cells?

To prevent leakage of fluids between cells Signup and view all the answers

Which type of junction is primarily responsible for allowing selective passage of ions and small molecules between adjacent cells?

Gap junctions Signup and view all the answers

What role do adhesion junctions play in animal tissues?

They connect cells to the extracellular matrix Signup and view all the answers

How are the four types of tissues in the animal body primarily differentiated?

By the type of extracellular matrix and cell organization Signup and view all the answers

Which of the following organ systems is involved in the homeostatic response to a rise in body temperature?

Nervous system Signup and view all the answers

What type of molecules are hydrophilic signaling molecules unable to do?

Cross the cell membrane Signup and view all the answers

In a negative feedback system responding to increased body temperature, what role do effectors play?

They produce a response that counteracts the change Signup and view all the answers

Which of the following is an example of a hydrophobic signaling molecule?

Steroids Signup and view all the answers

What occurs during a heart attack related to the coronary arteries?

One or more arteries become blocked, reducing blood supply Signup and view all the answers

What is the basic requirement for internal transport in larger multicellular animals?

An efficient circulatory system for substance distribution Signup and view all the answers

What role do hormones play in living organisms?

They help regulate metabolism, growth, and reproduction Signup and view all the answers

Where do hydrophilic signaling molecules bind when they reach a target cell?

To the cell membrane surface receptors Signup and view all the answers

What type of hormones are insulin and glucagon classified as?

Peptide hormones Signup and view all the answers

How are most hydrophilic signaling molecules transported in the body?

Attached to carrier proteins Signup and view all the answers

What is the primary function of the endocrine system?

To release and regulate hormones Signup and view all the answers

In which part of the cycle do steroids primarily exert their influence?

Inside the cell binding to intracellular receptors Signup and view all the answers

What is the primary reason for programmed cell death in multicellular organisms?

To remove damaged DNA cells Signup and view all the answers

Which of the following triggers apoptosis?

Signalling molecules from inside or outside the cell Signup and view all the answers

Why do lymphocytes die by apoptosis after an infection has been cleared?

They are no longer needed Signup and view all the answers

How does apoptosis contribute to the development of human hands in embryos?

By removing webbing between fingers Signup and view all the answers

Which statement about individuals with Type II diabetes is correct?

Their insulin receptors do not respond adequately Signup and view all the answers

What does the process of apoptosis ensure in a multicellular organism?

Regulation of the number of cells Signup and view all the answers

Which of the following best describes apoptosis?

A highly regulated cell death process Signup and view all the answers

What is one of the roles of apoptosis in response to infections?

To eliminate unnecessary immune cells Signup and view all the answers

What is the primary role of auxin (IAA) in plants?

To promote cell growth and expansion Signup and view all the answers

When a plant experiences phototropism, what causes the bend toward the light?

Longer cells on the shaded side Signup and view all the answers

Where is auxin primarily produced in a plant?

At the very top of the stem Signup and view all the answers

How does auxin influence the rate of growth on either side of the plant stem during phototropism?

It causes increased growth on the shaded side Signup and view all the answers

What is the significance of plant hormones being produced in low concentrations?

They can exert large effects despite small amounts Signup and view all the answers

What happens to the auxin distribution when a plant receives light from one direction?

It accumulates on the shaded side Signup and view all the answers

Which of the following correctly describes the mechanism of bending in plants due to phototropism?

Cells on the shaded side elongate while those on the sunny side do not Signup and view all the answers

Which statement about auxin's role in phototropism is incorrect?

Auxin functions only in bright sunlight Signup and view all the answers

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Description

Test your knowledge on the roles of signalling molecules in both animal and plant communication, as well as the functions of various components in the circulatory system. This quiz covers important concepts such as signal transduction, neurotransmitters, and the mechanisms of apoptosis. Challenge yourself and solidify your understanding of these biological processes.