Biology Chapter 5: Cell Size and Evolution

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Questions and Answers

What limits the efficiency of material exchange in larger cells or organisms?

Decreased volume relative to surface area

Constant surface area regardless of size

Increased surface area relative to volume

Faster increase in volume compared to surface area (correct)

What is the relationship between the size of animals and their metabolic rates?

Larger animals have lower metabolic rates relative to their size (correct)

Larger animals have higher metabolic rates than smaller ones

Metabolic rates are unaffected by animal size

Smaller animals typically have lower metabolic rates than larger animals

How does natural selection act upon phenotypes?

By influencing how organisms behave and adapt (correct)

By modifying the environment of organisms

By solely changing the genotype of organisms

By determining genetic makeup directly

What factors contribute to the phenotype of an organism?

Genotype and environmental conditions Signup and view all the answers

What structural adaptation is necessary for larger animals to support their mass?

Proportionately thicker bones Signup and view all the answers

What initiates the opening of sodium channels during action potential generation?

A strong enough stimulus reaching the threshold Signup and view all the answers

During which phase of action potential does the inside of the axon become positively charged?

Depolarization Signup and view all the answers

How can phenotypes and genotypes be categorized in evolution?

They can be either homologous or analogous Signup and view all the answers

What is the effect of potassium channels opening during the action potential process?

Potassium ions exit the neuron, causing repolarization Signup and view all the answers

What best describes the concept of form and function in evolutionary biology?

Morphology, physiology, and behavior collectively define phenotype and function Signup and view all the answers

What effect does an increase in organism size have on the physical laws related to strength?

Strength must increase more than volume to maintain status Signup and view all the answers

In which direction do action potentials propagate along the neuron?

In one direction along the axon Signup and view all the answers

What is the normal resting membrane potential of an axon before action potential generation?

-70 mV Signup and view all the answers

What role does elastin serve in tissues?

Allows tissues to stretch and return to original shape Signup and view all the answers

Which transport mechanism involves the movement of substances through the cells themselves?

Transcellular pathway Signup and view all the answers

In which type of tissues can water and small ions pass easily between cells?

Leaky epithelial tissues Signup and view all the answers

What distinguishes direct signaling from indirect signaling?

Direct signaling involves physical connectivity between cells Signup and view all the answers

Which component is essential for the transport of glucose from the gut lumen into the bloodstream?

Na+-glucose transporter Signup and view all the answers

What is required for the function of gap junctions in direct signaling?

Physical connection between cells Signup and view all the answers

What type of signaling occurs when a signaling molecule remains attached to the signaling cell's membrane?

Contact-dependent signaling Signup and view all the answers

What best describes the role of hyaluronan in tissues?

Keeps tissues hydrated and assists cell movement Signup and view all the answers

In indirect signaling, how do chemical messengers reach their target cells?

By diffusion through the extracellular fluid Signup and view all the answers

Which transporter moves glucose from inside the cell to the extracellular space?

GLUT2 transporter Signup and view all the answers

What primary function does the thalamus serve in the brain?

Processes and filters sensory information Signup and view all the answers

Which part of the brain connects to the pituitary gland?

Hypothalamus Signup and view all the answers

How does the hypothalamus contribute to homeostasis?

By regulating body temperature, hunger, and thirst Signup and view all the answers

Which hormone is produced by the pineal gland?

Melatonin Signup and view all the answers

What role does the limbic system play in the brain?

Managing emotions and memory Signup and view all the answers

Which part of the brain is primarily responsible for processing fear and anger?

Amygdala Signup and view all the answers

Which of the following does NOT pass through the thalamus?

Smell Signup and view all the answers

What is the primary function of the hypothalamus in terms of bodily functions?

Maintaining body stability and balance Signup and view all the answers

What is the primary role of Broca's area?

To control speech production Signup and view all the answers

Which of the following best describes the function of the peripheral nervous system (PNS)?

It carries messages between the brain, spinal cord, and the rest of the body. Signup and view all the answers

Which brain structure sits at the back of the brain and is involved in various functions?

Epithalamus Signup and view all the answers

What is one of the primary functions of the cerebellum?

To coordinate movements Signup and view all the answers

What type of nerve is the optic nerve categorized as?

Cranial nerve Signup and view all the answers

What role does the prefrontal cortex play in human function?

Facilitating complex thinking and decision-making Signup and view all the answers

Which nerve is associated with sending pain signals from the leg to the brain?

Sciatic nerve Signup and view all the answers

How many pairs of cranial nerves are there?

12 pairs Signup and view all the answers

What is NOT a function of the association cortices?

Transmitting sensory information Signup and view all the answers

Which of the following is a primary function of the spinal nerves?

Sending sensory information from the body to the brain Signup and view all the answers

What characterizes the location of Broca's area?

In the motor association cortex, typically in the left hemisphere Signup and view all the answers

Which of the following statements about the prefrontal cortex is FALSE?

It regulates basic life functions such as heartbeat. Signup and view all the answers

Study Notes

Rate of Exchange

Smaller cells have a higher surface area to volume ratio, which is important for efficient material exchange.
As cells or organisms increase in size, their volume increases faster than their surface area.
This can limit the efficiency of material exchange.

Size and Scale

Larger animals need proportionally thicker bones to support their greater mass.
This is due to the relationship between cross-sectional area and volume (mass).
Larger animals have lower metabolic rates relative to their size compared to smaller animals.

Form and Function

Phenotype encompasses an organism's morphology (form), physiology (function), and behavior.
The phenotype is what natural selection acts upon.
Genotype refers to an organism's genetic makeup.
Evolutionary changes occur due to interactions between genotype and environment.
Organisms adapt to their surroundings through natural selection.

Evolution

Convergent evolution occurs when unrelated organisms evolve similar traits due to similar environmental pressures.
Analogous traits are similar in function but have different evolutionary origins.
Divergent evolution happens when related organisms evolve different traits due to different selective pressures.
Homologous traits share a common evolutionary origin.

Cell-Cell Communication

Direct signaling involves communication between physically connected cells.
Gap junctions create direct connections between cells, allowing signaling molecules to move between cytoplasms.
In contact-dependent signaling, a signaling molecule attached to the signaling cell membrane binds to a receptor on the target cell.
Indirect signaling utilizes chemical messengers that travel to target cells.
Chemical messengers are released from the signaling cell into the extracellular environment.

Transcellular and Paracellular Pathways

Transcellular pathway involves the movement of substances through cells.
For example, glucose transport in gut epithelial cells involves:
- Na+-glucose transporter: Uses a sodium gradient to bring glucose into the cell.
- GLUT2 transporter: Moves glucose from the cell to the extracellular space.
Paracellular pathway involves the movement of substances between cells (through gaps).
Leaky epithelial tissues allow for the movement of water and small ions between cells.

Nervous System

The central nervous system (CNS) consists of the brain and spinal cord.
The brain is responsible for processing information and generating responses.
Sensory information is processed by the thalamus before reaching the cerebral cortex.
The hypothalamus functions as a control center for maintaining homeostasis.
The limbic system plays a crucial role in emotions and memory.
The peripheral nervous system (PNS) connects the CNS to the rest of the body.
Cranial nerves originate from the brainstem and carry information from the head and face.
Spinal nerves emerge from the spinal cord and control the body's extremities.

Neuron Signaling

Neurons transmit information through electrical signals.
Action potentials are rapid changes in a neuron's charge that allow it to send a signal.
Voltage-gated ion channels open in response to changes in charge, allowing specific ions to enter or leave the neuron.
Action potential propagation involves the sequential opening of sodium and potassium channels, creating a wave of depolarization that travels down the axon.
Action potentials can only move in one direction along the neuron.
The process of action potential generation includes:
- Resting state: The axon is at rest with a negative charge inside compared to the outside.
- Threshold: A strong enough stimulus triggers the opening of sodium channels.
- Depolarization: Sodium ions rush into the axon, making the inside positive.
- Action potential peak: Sodium channels close, and potassium channels open, causing the inside to repolarize.
- Repolarization: Potassium ions flow out, making the inside negative again.

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Description

Explore the fascinating concepts of cell size, rate of exchange, and evolutionary adaptations in this quiz. Understand how size impacts efficiency in material exchange, the implications for larger organisms, and the role of phenotype in natural selection. Test your knowledge on the intricate relationship between genotype and environment!