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?

<p>Fas ligand pathway (B)</p> Signup and view all the answers

What is a distinguishing feature of neurotransmitters compared to hormones?

<p>Neurotransmitters typically act locally and quickly. (B)</p> Signup and view all the answers

Which statement about cytokinins is accurate?

<p>They play a key role in plant cell division. (B)</p> Signup and view all the answers

Apoptosis can occur through which of the following mechanisms?

<p>Both intrinsic and extrinsic pathways (A)</p> Signup and view all the answers

What function do arteries serve in the circulatory system?

<p>They carry blood away from the heart. (B)</p> Signup and view all the answers

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

<p>Capillaries (C)</p> Signup and view all the answers

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

<p>They have thick walls. (D)</p> Signup and view all the answers

How do substances diffuse between capillaries and cells?

<p>From interstitial fluid to/from cells. (B)</p> Signup and view all the answers

What prevents the flow of fluid in lymph vessels?

<p>They have closed ends. (D)</p> Signup and view all the answers

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

<p>They have a single layer of cells. (B)</p> Signup and view all the answers

Which statement correctly describes capillary networks?

<p>They provide access to almost every cell in the body. (C)</p> Signup and view all the answers

What role does interstitial fluid play in the exchange process?

<p>It facilitates diffusion between cells and capillaries. (C)</p> Signup and view all the answers

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

<p>To prevent leakage of fluids between cells (D)</p> 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?

<p>Gap junctions (A)</p> Signup and view all the answers

What role do adhesion junctions play in animal tissues?

<p>They connect cells to the extracellular matrix (A)</p> Signup and view all the answers

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

<p>By the type of extracellular matrix and cell organization (A)</p> Signup and view all the answers

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

<p>Nervous system (C)</p> Signup and view all the answers

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

<p>Cross the cell membrane (D)</p> Signup and view all the answers

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

<p>They produce a response that counteracts the change (A)</p> Signup and view all the answers

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

<p>Steroids (B)</p> Signup and view all the answers

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

<p>One or more arteries become blocked, reducing blood supply (B)</p> Signup and view all the answers

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

<p>An efficient circulatory system for substance distribution (C)</p> Signup and view all the answers

What role do hormones play in living organisms?

<p>They help regulate metabolism, growth, and reproduction (C)</p> Signup and view all the answers

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

<p>To the cell membrane surface receptors (B)</p> Signup and view all the answers

What type of hormones are insulin and glucagon classified as?

<p>Peptide hormones (D)</p> Signup and view all the answers

How are most hydrophilic signaling molecules transported in the body?

<p>Attached to carrier proteins (D)</p> Signup and view all the answers

What is the primary function of the endocrine system?

<p>To release and regulate hormones (A)</p> Signup and view all the answers

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

<p>Inside the cell binding to intracellular receptors (D)</p> Signup and view all the answers

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

<p>To remove damaged DNA cells (C)</p> Signup and view all the answers

Which of the following triggers apoptosis?

<p>Signalling molecules from inside or outside the cell (D)</p> Signup and view all the answers

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

<p>They are no longer needed (D)</p> Signup and view all the answers

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

<p>By removing webbing between fingers (D)</p> Signup and view all the answers

Which statement about individuals with Type II diabetes is correct?

<p>Their insulin receptors do not respond adequately (B)</p> Signup and view all the answers

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

<p>Regulation of the number of cells (D)</p> Signup and view all the answers

Which of the following best describes apoptosis?

<p>A highly regulated cell death process (C)</p> Signup and view all the answers

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

<p>To eliminate unnecessary immune cells (B)</p> Signup and view all the answers

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

<p>To promote cell growth and expansion (A)</p> Signup and view all the answers

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

<p>Longer cells on the shaded side (C)</p> Signup and view all the answers

Where is auxin primarily produced in a plant?

<p>At the very top of the stem (C)</p> Signup and view all the answers

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

<p>It causes increased growth on the shaded side (D)</p> Signup and view all the answers

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

<p>They can exert large effects despite small amounts (C)</p> Signup and view all the answers

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

<p>It accumulates on the shaded side (D)</p> Signup and view all the answers

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

<p>Cells on the shaded side elongate while those on the sunny side do not (A)</p> Signup and view all the answers

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

<p>Auxin functions only in bright sunlight (D)</p> Signup and view all the answers

Flashcards

Animal Cell Junctions

Structures that connect animal cells, facilitating communication and interaction. There are three main types: tight junctions, adhesion junctions, and gap junctions.

Tight Junction

Junctions that form a watertight seal between animal cells, preventing leakage. Forms a barrier to substances.

Adhesion Junction

Junctions that connect animal cells mechanically, providing structural integrity and resisting mechanical stress. Act as an adhesive.

Gap Junction

Junctions that create channels between animal cells, allowing communication and passage of small molecules. Act as a connection passageway

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Animal Tissues

Groups of specialized cells that perform specific functions in the animal body.  Four main types: epithelial, connective, muscle, and nervous.

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Homeostasis

Maintaining a stable internal environment in an organism.

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Negative Feedback System

A homeostatic mechanism where a change in a variable triggers a response that counteracts the change, returning the variable to normal range

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Internal Transport (Animals)

The process of moving substances within and around the body of multicellular animals. Larger animals require a circulatory system to supply cells with oxygen and nutrients and remove waste products.

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Blood vessels

Pipes that carry blood throughout the body.

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Arteries

Blood vessels that carry blood away from the heart.

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Capillaries

Small blood vessels where gas and material exchange occurs.

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Veins

Blood vessels that carry blood back to the heart.

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Material Exchange

The process of substances moving in and out of capillaries.

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Capillary Walls

Thin walls that enable easy passage of materials.

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Interstitial Fluid

Fluid surrounding cells where material exchange occurs.

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Lymphatic System

System of vessels that collects fluid from tissues.

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Cell Signalling

A process where cells communicate with each other by releasing signalling molecules that travel to target cells and trigger specific responses.

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Autocrine Signalling

A type of cell signalling where the signalling molecule acts on the same cell that released it.

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Paracrine Signalling

A type of cell signalling where the signalling molecule acts on nearby target cells.

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Endocrine Signalling

A type of cell signalling where the signalling molecule travels through the bloodstream to reach distant target cells.

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Gap Junction Signalling

A type of cell signalling where signalling molecules pass directly from one cell to another through specialized channels called gap junctions.

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Hydrophobic Signalling Molecules

Signalling molecules that can easily pass through cell membranes, often acting on intracellular receptors.

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Hydrophilic Signalling Molecules

Signalling molecules that cannot easily pass through cell membranes, often acting on receptors on the cell surface.

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Stimulus-Response Model

A basic model of how cells respond to stimuli, involving reception of the signal, signal transduction, and a cellular response.

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What do hormones do?

Hormones are signalling molecules that are released in small amounts and help regulate metabolism, growth, and reproduction in living things.

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What is the endocrine system?

The endocrine system is composed of glands and organs that produce and release hormones. It regulates many body functions, including metabolism, growth, and reproduction.

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Insulin

A peptide hormone released from the pancreas that helps regulate blood sugar levels. It attaches to cell surface receptors and allows glucose uptake into cells.

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Glucagon

A peptide hormone released from the pancreas that helps regulate blood sugar levels. It works in conjunction with insulin to maintain glucose balance.

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Steroid hormones

A type of hormone that is hydrophobic and can cross the cell membrane. They bind to intracellular receptors.

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Peptide hormones

A type of hormone that is hydrophilic and cannot cross the cell membrane. They bind to receptors on the cell surface.

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Plant Hormones

Chemical messengers produced in low concentrations that regulate plant growth and development. They can work independently or together to influence different aspects of plant life.

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Auxin (IAA)

A plant hormone primarily produced in actively growing parts of the plant like the stem tip. It plays a crucial role in cell growth and elongation, enabling plants to grow upward.

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Phototropism

The growth of a plant in response to light. The stem of a plant will bend towards a light source.

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How does Auxin cause Phototropism?

When a plant receives light from one side, Auxin produced at the stem tip diffuses to the shaded side of the stem. This uneven distribution of Auxin causes the cells on the shaded side to grow longer, causing the stem to bend towards the light.

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Cell Expansion

The process of cells increasing in size, leading to the growth of plant tissues.

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Plant Growth Response

The way a plant responds to environmental stimuli like light, gravity, and water. The plant will adjust its growth pattern to optimize its survival and reproduction.

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Hormone's Role in Plant Physiology

Plant hormones are essential for regulating various processes in plants, including growth, development, reproduction, and response to environmental cues. They work together in a complex network to ensure plant survival and reproduction.

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Plant Hormones vs. Animal Hormones

While both plant and animal hormones are chemical messengers that regulate growth and development, they have different structures and functions.

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Apoptosis

Programmed cell death that occurs naturally in multicellular organisms, removing unwanted or damaged cells.

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Why is apoptosis needed?

Apoptosis is essential for regulating cell numbers, removing unnecessary cells, and eliminating cells with damaged DNA.

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Apoptosis example: Lymphocytes

Lymphocytes responsible for producing antibodies die via apoptosis after an infection is cleared, as they are no longer needed.

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Apoptosis example: Webbing

Webbing between fingers in embryos is removed by apoptosis during development, forming distinct fingers.

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Triggers of Apoptosis

Apoptosis is initiated by signalling molecules that originate either inside or outside the cell.

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Type II Diabetes: Insulin Resistance

Individuals with Type II diabetes produce insulin, but their cells don't respond to it properly, resulting in high blood sugar.

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Cell Signalling in Apoptosis

Apoptosis is a highly regulated process, involving cell signalling where messages are sent between cells to trigger death.

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Apoptosis: A Precise Process

Apoptosis ensures a controlled cell death, preventing harmful inflammation or debris that can damage other cells.

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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.

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