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2 years ago

17. Biologists have hypothesized that echinoderms are closely related to chordates because both groups are deuterostomes.

Biology

2 answers:

alexira [117]2 years ago

4 0

Answer:

True

Explanation:

15- happens daily

16- courtship

erma4kov [3.2K]2 years ago

3 0

The answer would be true

Deuterostomes are superphylum of Animalia kingdom in taxonomy. The word means the second mouth in the Greek language which characterizes this group with an anus, opening on the other sides of the mouth to dump waste. The member of this superphylum is Chordata, Hemichordata, and Echinodermata.

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In humans, sperm can survive _____ within the female reproductive tract.view available hint(s)in humans, sperm can survive _____

olga55 [171]

In humans sperms can survive 3 -5 days within the female reproductive tract.
The ideal time of fertilization is around ovulation when the egg is in the fallopian tube. After travelling through the vaginal canal, the strongest sperm make it to the cervix. From here, the sperm must travel through the uterus and into one of the fallopian tubes.

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2 years ago

If bears find insects after they move decaying logs, they more frequently move decaying logs. This most clearly indicates that f

Alex777 [14]

Answer:

Reinforcement

Explanation:

Reinforcement can be referred to as anything that can be used to increase, enhance or strengthen a desirable behavior in a person or an organism. Reinforcement is of two types, they include positive reinforcement and negative reinforcement. Positive reinforcement has to do with adding a reward in order to enhance a desirable behavior, while negative reinforcement has to do with removing an undesirable thing in order to strengthen a desirable behavior.

From the question asked, because the presence of insects after moving the decaying logs increased the frequency at which the bears moved the decaying logs, the finding of the insects is, therefore, a reinforcement. The finding of the enhanced or strengthened the desirable behavior.

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2 years ago

Describe three main features inside a prokaryotic cell.

Art [367]

The three main features of a prokaryotic cell
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Externally prokaryotic cells have: 1. Capsules. 2. Flagellum. A tail 3. Pili. A hair-like structure on its surface.

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2 years ago

Read 2 more answers

Which of the following is true about scientific inquiries? A. Scientific inquiries never require any mathematical knowledge or t

masya89 [10]

C because a scitienfic injury is a process where you make a hypothesis based off something you kinda of know about then you test your hypothesis by doing an expedient and multiple trials

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2 years ago

6. In fossils, what anatomical evidence indicates that gills were present?

Phoenix [80]

Answer and explanation:

6. In fossils, what anatomical evidence indicates that gills were present?

The anatomical evidence found in the fossils, such as special bone structures in the shoulders and skulls to support the gills, allows us to know the existence of these structures in some ancient species.

7. Many transitional species had gills, which means they lived in aquatic environments.

Gills are structures which allow people to breathe underwater, and many evolutionary transition species had them, such as the Tiktaalik, which also had lungs.

The existence of gill and lung respiration is what leads us to think that transition species were the first to leave the aquatic habitat to become terrestrial tetrapods.

8. Lungs allow an animal to breathe air. Why did this adaptation evolve?

Species considered transitional between fish and land animals were equipped with both gills and lungs.

It is suggested that the appearance of the lungs is due to the lower concentration of oxygen in the water and the need to obtain oxygen from another source, such as air, where the oxygen concentration is higher. In these circumstances, increased oxygen demand forced some animals to leave the aquatic habitat.

9. Tetrapods use lungs to breathe. Do any modern tetrapods have gills? Explain.

Some present-day tetrapods - such as salamanders, toads and frogs - are amphibians, and in their larval stage they remain in an aquatic habitat, so they are equipped with gills during this stage of their life cycle.

In amphibians like the frog, the passage from the larval stage to the adult stage involves a process called metamorphosis, in which the gills disappear and the lungs develop, in addition to the appearance of the four limbs, which are absent in the larva.

13. Most modern tetrapods have five digits on front limbs and five digits on back limbs, although some species have fewer. How does this number compare to the number of digits on the limbs of transitional fossil forms?

The transitional species originally had fins, but fossils of the first tetrapods have been found with developed limbs and five or more digits, representing an equal or greater number of digits than current species.

An example of a larger number of toes is represented by the genus Acanthostega, with eight toes on each limb.

14. Why do many of the transitional fossils between fish and tetrapods have flat heads?

Many of the transition fossils between fish and tetrapods have flat heads, from top to bottom, because these species participated in the transition between aquatic and terrestrial habitat, adapted to living in shallower waters near the surface, and with gill and lung breathing capacity.

15. How did the anatomy of the shoulder and head change during tetrapod evolution?

The changes in the anatomy of the shoulder and head during the evolution of the tetrapod were basically three:

The bony skeleton of the shoulder is separated from the skull, which in aquatic animals was attached.
The appearance of the neck, between both structures.
Development of an independent movement of the skull, with respect to the shoulder and the rest of the body.

16. Tiktaalik and Acanthostega are fossil species have characteristics unique to fish as well as characteristics found in fish and tetrapods. Describe the characteristics of lobe-finned fish that are similar to those of tetrapods.

Lobe-finned fish -called sarcopterygians- like dipnoi, are lungfish, given the existence of functional lungs in their body. Another characteristic of lobefish is that each of their fins is attached to a single bone, as in the case of the humerus and femur of mammals.

The existence of lungs and the attachment of the limbs to a bone are common features among lobed finfish and tetrapods.

17. Which lobe-finned fish is alive today?

The coelacanth is one of the oldest species of fish that exist, as they are lobe-finned fish that were thought to be extinct, but still exist.

The characteristic of possessing lungs and bony skeleton relates them to the actual lung fishes and to the terrestrial vertebrates.

18. Acanthostega and Icythyostega have been called fish-like tetrapods. Explain why they are described as such and describe the environment in which they probably lived.

Both the Acanthostega and the Icythyostega were animals characterized by having four extremities and be equipped with gills and lungs at the same time, which determines that they are called tetrapods similar to fish.

Their characteristics made them suitable for living in aquatic and terrestrial environments, so they probably inhabited shallow waters or even the surface of the earth.

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2 years ago