Herbivores Digestive Mechanisms

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Questions and Answers

What percentage of their energy may advanced fishes use to extract oxygen from water?

20% (correct)

30%

10%

Why must respiratory surfaces remain moist?

To maintain a stable temperature.

To prevent the invasion of pathogens.

To allow diffusion of gases. (correct)

To facilitate nutrient absorption.

Which of the following respiratory systems is characteristic of insects?

Tracheal system (correct)

Lungs

Gills

Branchial pump

What method do fish gills use to maximize oxygen extraction?

Counter current flow Signup and view all the answers

Which respiratory structure is considered the least efficient in invertebrates?

Ventilated lungs Signup and view all the answers

What role does insect blood play in respiration?

No direct role in oxygen transport Signup and view all the answers

Which of the following organisms primarily utilizes invaginations for breathing?

Terrestrial vertebrates Signup and view all the answers

What is the primary function of spiracles in the tracheal system of insects?

Gas exchange Signup and view all the answers

Which gas has the greatest effect on respiratory rate?

Carbon dioxide Signup and view all the answers

What is the most widespread respiratory pigment in vertebrates?

Haemoglobin Signup and view all the answers

What is the role of haemoglobin in the body?

To transport oxygen and carbon dioxide Signup and view all the answers

How do invertebrates primarily transport respiratory gases?

Carrying them dissolved in body fluids Signup and view all the answers

What must organic compounds undergo before animals can absorb them?

They must be digested into simpler molecules Signup and view all the answers

What process allows animals to obtain energy from food?

Digestion and oxidation Signup and view all the answers

Which pigment is found in crustaceans and serves a similar function to haemoglobin?

Hemocyanin Signup and view all the answers

What happens to food not immediately used by the body?

It is stored for future use Signup and view all the answers

What proportion of the dry weight of faeces in adults is made up of bacteria?

Approximately one-third Signup and view all the answers

Which vitamin is synthesized by bacteria found in faeces?

Vitamin K Signup and view all the answers

What is the primary factor in determining whether a parasite can survive in its host?

The host's immune response Signup and view all the answers

What term describes an animal's inability to eliminate a parasite before it becomes established?

Susceptible Signup and view all the answers

Which type of immunity does not depend on prior exposure to an invader?

Innate immunity Signup and view all the answers

What type of barriers does the integument provide against invading organisms?

Physical and chemical barriers Signup and view all the answers

What happens to some parasites after a host recovers clinically?

They remain and reproduce slowly Signup and view all the answers

What can be found in the secretions of the alimentary tract that acts as a chemical defense?

Enzymes Signup and view all the answers

What role does the pyloric sphincter play in digestion?

It regulates the flow of food into the intestine. Signup and view all the answers

How does the structure of the intestine facilitate absorption in vertebrates?

Through extensive coiling and development of folds. Signup and view all the answers

In which type of animal might the intestine primarily function as a pathway for waste?

Invertebrates with extensive digestive diverticula. Signup and view all the answers

What feature is common in the intestines of mammals?

Intestinal length exceeding eight times body length. Signup and view all the answers

Which of the following components significantly increases the surface area of the intestinal cavity?

Microvilli. Signup and view all the answers

What process occurs primarily in the large intestine?

Reabsorption of water and formation of feces. Signup and view all the answers

In which animals is the reabsorption of water particularly crucial due to their living conditions?

Insects in dry environments. Signup and view all the answers

What type of feces do reptiles and birds generally produce?

White paste-like containing uric acid. Signup and view all the answers

What is the primary function of grinding and cutting mandibles in locusts?

To disrupt cellulose cell walls for faster digestion Signup and view all the answers

What adaptation allows herbivores to digest food that carnivores cannot?

The use of specialized teeth to break down cellulose Signup and view all the answers

What is a characteristic of fluid feeding in parasites?

They extract nutrients directly from the host fluids Signup and view all the answers

In which organisms does intracellular digestion primarily occur?

Protozoa and sponges Signup and view all the answers

What is one major limitation of intracellular digestion?

Only small particles can be processed Signup and view all the answers

What defines extracellular digestion in animals?

Food is exposed to diverse mechanical, chemical, and enzymatic processes outside cells Signup and view all the answers

How are the metazoan alimentary canals structured?

They include five distinct functional regions Signup and view all the answers

What role does the lumen of alimentary canals play in digestion?

It contains specialized cells for secretion of digestive juices Signup and view all the answers

Study Notes

Energy Costs in Respiration

Advanced fishes expend up to 20% of their energy on oxygen extraction from water.
Mammals have a significantly lower respiration energy cost, utilizing only 1% to 2% of their resting metabolism.

Structure of Respiratory Surfaces

Respiratory surfaces need to be thin and moist to facilitate gas diffusion.
Air breathers typically have invaginations (lungs, tracheae) for air intake, while aquatic creatures have evaginations (gills) suitable for extracting oxygen from water.

Tracheal System in Invertebrates

Insects, centipedes, millipedes, and some spiders possess a tracheal respiratory system that is efficient and direct.
Tracheae are branching tubes reaching all body parts, with tracheoles terminating at cell membranes for gas exchange.
Air enters through spiracles and bypasses the circulatory system in respiration; insect blood does not transport oxygen.

Function and Structure of Gills

Gills serve as effective respiratory systems for aquatic life, with internal gills being the most efficient.
Fish gills feature thin filamentous structures that allow for countercurrent flow, maximizing oxygen extraction.
Water moved over the gills by an efficient pumping mechanism facilitates continuous gas exchange.

Lung Structures in Invertebrates

Some invertebrates, like pulmonate snails and certain crustaceans, possess rudimentary lungs with less efficient ventilation compared to vertebrates.
Ventilated lungs in terrestrial vertebrates enable rhythmic air exchange.

Respiratory Gases and Pigments

Low water solubility of oxygen limits gas transport in some invertebrates, necessitating respiratory pigments for efficient oxygen transport.
Haemoglobin is the most widespread respiratory pigment in vertebrates, allowing oxygen binding and release based on prevailing oxygen concentrations.
Invertebrate pigments include hemocyanin and chlorocruorin, differing in composition and function.

Overview of Digestion

All organisms derive energy from transforming complex external compounds into simpler forms, primarily from sunlight captured by plants.
Animals are heterotrophic, relying on digestion to convert food into absorbable units.

Mechanisms of Digestion

Digestion involves mechanical and chemical breakdown of food, transforming large particles into soluble molecules for absorption into the circulatory system.
Herbivores possess specialized teeth (e.g., grinding molars) to disrupt tough plant materials, aided by intestinal microorganisms for digestion.

Types of Digestion

Digestion can be intracellular (within cells) or extracellular (in an alimentary canal).
Extracellular digestion allows for processing larger food masses and involves specialized cells for secretion and absorption.

Structure of the Alimentary Canal

The alimentary canal has five main regions facilitating digestion: reception, conduction/storage, grinding/early digestion, terminal digestion/absorption, and water absorption/concentration of solids.
In vertebrates, the intestine features adaptations like folding and villi that greatly enhance surface area for absorption.

Role of the Large Intestine

The large intestine reabsorbs water to form solid or semisolid feces, crucial for waste elimination.
Invertebrates often rely on diverticula for extensive processing, while vertebrates utilize the intestine for both digestion and nutrient absorption.

Microbiota in Digestion

The human colon houses significant microbial populations, contributing to waste degradation and nutrient synthesis, notably vitamins.

Summary of Immune Function

The immune system is vital for animal survival, protecting against a wide array of potential parasites and pathogens in the environment.
Resistance to parasites is influenced by both innate and acquired immunity; innate immunity offers immediate, nonspecific defense, while acquired immunity develops specific responses over time.

Defense Mechanisms

Physical barriers, like the integument, along with antimicrobial substances in body secretions, enhance defense against pathogen invasion.
Chemical defenses include acidic environments in body cavities and digestive tracts, further preventing infection.

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Description

Explore how various herbivorous animals, including insects and mammals, utilize specialized structures for breaking down tough plant materials. This quiz delves into the grinding mandibles of locusts and the molars of horses and cattle, highlighting their role in digestion and nutrient conversion. Understand the differences in digestion processes between herbivores and carnivores.