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Cloud [144]
4 years ago
6

Which statement best describes the human immunodeficiency virus (HIV) that has been shown to cause AIDS in humans?

Biology
1 answer:
Lera25 [3.4K]4 years ago
3 0
Were are the statements lol
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The egyptian plover is a bird best known for its symbiotic relationship with what host animal?
EastWind [94]

Answer:

Nile crocodile

Explanation:

The Egyptian plover is a small bird with a very unusual friend in the animal kingdom. This bird actually has a symbiotic relationship with the Nile crocodile. It may seem very odd relationship, but it is one that works excellently for both sides. The crocodiles have sharp set of teeth, but they have spaces between them and can not move their jaws sideways. Because of this, very often there's meat stuck between the teeth of the crocodiles, and this is when the Egyptian plover comes on the scene. This little bird actually gets into the open mouth of the crocodiles, picking up the pieces of meat that have stuck between their teeth, and then continuing with its mission. The crocodiles do not try to eat this bird, but instead they stand still while it does its job. The relationship is beneficial for both sides, as the crocodiles have their own personal ''dentist'', while the plover gets free food.

5 0
3 years ago
What are other health issues in areas impacted by Ebola?
MakcuM [25]
It destroys the internal organs until they fail.
6 0
4 years ago
Arrange these muscle contraction events in the correct order.
erastovalidia [21]

Answer:

 1. nerve stimulus

4. calcium channels open

10. acetylcholine vesicles move to endplate

7. exocytosis occurs releasing acetylcholine into synaptic cleft

3. acetylcholine binds to receptor

6. impulse rides along sarcolemma

9. impulse enters the cells via the t-tubule

5. sarcoplasmic reticulum releases calcium

8. calcium binds to troponin moving tropomyosin out of the way

2. myosin attaches to actin causing a twitch

Explanation:  

The central nervous system generates an action potential (<u>1</u>) that travels to the muscle fiber activating the calcium channels (<u>4</u>). Calcium triggers vesicles fusion to the presynaptic membrane (<u>10)</u> releasing acetylcholine (Ach) into the synaptic space (<u>7</u>). Once there, Ach binds to its receptors (<u>3</u>) on the postsynaptic membrane of the skeletal muscle fiber, causing ion channels to open. Positively charged sodium ions cross the membrane to get into the muscle fiber (sarcoplasm) and potassium leaves the cell. The difference in charges caused by these ions transport charges positively the muscle fiber membrane (<u>6</u>). It depolarizes. The action potential enters the t-tubules (<u>9</u>) depolarizing the inner portion of the muscle fiber.  

Contraction initiates when the action potential depolarizes the inner portion of the muscle fiber. Calcium channels activate in the T tubules membrane, releasing calcium into the sarcolemma (<u>5</u>). At this point, the muscle is at rest, and the tropomyosin is inhibiting the attraction strengths between myosin and actin filaments. <em>Tropomyosin is obstructing binding sites for myosin on the thin filament</em>. When calcium binds to troponin C, troponin T alters the tropomyosin position by moving it and unblocking the binding sites (<u>8)</u>. Myosin heads join to the uncovered actin-binding points forming cross-bridges <u>(2</u>), and while doing so, ATP turns into ADP and inorganic phosphate, which is released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. The power stroke initiates when the myosin cross-bridge binds to actin (<u>2</u>). As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament.  Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Finally, Z-bands are pulled toward each other, shortening the sarcomere and the I-band, producing muscle fiber contraction.

6 0
3 years ago
The organisms of which domain are organized according to their shape? A. Bacteria B. Archaea C. Eukaryota
-Dominant- [34]
The three domain system is develop by Carl Woese and is used to classify biological organisms. Under these would be bacteria,archaea and eukaryota. There are also kingdoms namely archaebacteria,fungi, plantae, etc.The answer on this question would be letter b. archaea
6 0
3 years ago
Two different species live in the same area and eat the same type of food. What is present between
joja [24]

Answer:

Diversity

Explanation:

Two different species live in the same area and eat the same type of food. I

Said diversity they live together.................

I tried my best

4 0
3 years ago
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