1. A flexible, supporting structure found only in chordates is the A. nerve net
B. notochord
C. pharyngeal slits
D. dorsal fin.

2. Ancient chordates are thought to be most closely related to which of the following species?
A. spiders
B. earthworms
C. octopi
D. sea stars

Digestion refers to the chemical and mechanical processes that break down food.

What is digestion?

Digestion is the process through which food moves through our bodies, with the goal of giving energy to the body or constructing new cellularcomponents and tissues, such as muscle and fat.

How does digestion take place?

• When food enters the mouth, it is mechanicallydigested (chewing) and becomes when it comes into touch with saliva. Saliva contains salivary amylase, which helps food digest starch. Salivaryamylase is a digestive enzyme that starts the digestion of starch in meals.
• The food will be in the form of a small, round slurry mass known as a bolus after mastication and starch digestion.It moves down the esophagus and into the stomach due to peristalsis.
• In the stomach, gastric fluids beginprotein digestion.Pepsin and hydrochloricacid are the main components of these juices. Because the HCl may harm the stomach wall, the stomach secretesmucus, which forms a sticky covering that protects the stomach from the acid's harmful effects.
• Peristalsis, a mechanical mixingprocess that permits the mass of food to interact with the digestiveenzymes, occurs concurrently with protein digestion.
• After some time, a thick liquid called chyme is produced, which enters the duodenum and mixes with pancreatic digestive enzymes and liver bile juice before passing through the smallintestine. After the chyme has been entirely digested, it is taken into the bloodstream, where it forms a stickybarrier that protects the body from the acid's harmful effects.

Thus, we can conclude that option A is correct.

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Answer:

Changes in the basal levels that are on the bottom of the food chain.

Explanation:

Trophic levels are represented by steps in the food chain. In a simplified diagram, the first basal level is represented by primary producer organisms that include plants and algae. The herbivores are localized in the second place, while in the final levels it is possible to find carnivores and predatory species. It is well known that the changes in the basal trophic levels of this chain (i.e., changes in the first and the second levels) may alter the equilibrium of the food chain and consequently have effects on the stability of the ecosystem.

The correct answer form all of the given options is (c) The birds Darwin found in the Galapagos were different types of finches, not separate types of birds.

Further explanation:

Adaptation theory given by Charles Darwin is also called survival of the fittest theory or just survival theory, it explains the ability of the organism to adapt to the changes of the environment over generations and give rise to new form of species.

Darwin named this theory natural selection stated that;

• Adaptation is the survival process through which species become suited to the surrounding environmental changes. There is process called genetic variation in which species with best suited genes or characteristics has better chances to survive and reproduce.
• Over a period of several generations the genetic make-up of the surviving species will slowly change and become completely adapted to the need of the physical environment.
• Some of the most important distinguished feature Darwin noticed regarding different species was found on nearby island of Galapagos which had similar but not identicalspecies of finches living on them, each finches species had distinguishable feature but they are adeptly suited to their respected environment. Some of them had large and tough beak whereas others had sharp and thin beak. Finally he noticed that finches found on the Galapagos island were similar to mainland Ecuador but different form elsewhere.

• Darwin furthermore noticed the turtles from two different islands one turtle population had short legs and they ate food that was low on the groundand the other one had long legs because the food source was much higher up. So the theory was that when the turtle migrated to another island in the search of food, there the food source was much higher up so, the turtle with long legs survived and evolved.

There is internal adaptation as well which cannot be seen from outside the body for example vertebrates adapting to regulate their body temperature.

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Answer Details:

Grade: High school

Subjest: Biology

Chapter: Darwin’s theory of evolution  

Keywords  

Finches, adaptation, species, natural selection, characteristics, genes, genetic variation, Galapagos.

Answer:

B

Explanation:

Carbohydrates are large molecules made up of mono saccharides and are used by organisms for energy storage.