Answer:
A concentration gradient occurs when the concentration of particles is higher in one area than another. In passive transport, particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower concentration, until they are evenly spaced.
Explanation:
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Answer:
Sponges use <em><u>choanocytes</u></em> or <em><u>flagellated channels</u></em> to get nutrients from the feeding cells to other parts of their body.
Explanation:
Sponges are marine animals with a sac-shaped body. The epidermis is composed of polygonal flat cells called pinacocytes and pores protected by porocytes. Under the epidermis, there is a protein matrix called mesenchyme, which is composed of spicules and <em><u>amibocytes</u></em>. By the interior side of the sponge, there are the<em><u> choanocytes</u></em>. These are ovoid cells that can be shaping the spongocoele (internal cavity of the sponge), with an extreme attached to the mesenchyme and the other extreme projected to the spongocoele, or can be grouped in spaces called <em><u>flagellated channels</u></em>.
These animals depend on water to get oxygen and food to the inside of the sac and take excrements and reproductive cells to the outside. Sponges <em>feed on small detritus particles and suspending organisms</em> that get near the animal by water streams produced by choanocytes.
Particle size is essential. Only the small ones can get through the flagellated channels, where they get stuck to the choanocytes and are encapsulated by the cells. If the choanocytes are too small, the particle is transferred to the amibocytes for digestion. These last ones also act as food storages. Excrement products are dragged by a water stream.
Answer:
Nonrenewable energy resources, like coal, nuclear, oil, and natural gas, are available in limited supplies. This is usually due to the long time it takes for them to be replenished. Renewable resources are replenished naturally and over relatively short periods of time.
Answer: Colonial organisms are the result of many identical individuals joining together to form a colony. These cells are partly dependent on each other to start with. But, later evolutionary events resulted in the obligatory relationships among them resulted in multicellularity.
Answer:
Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier? D) Inducing TNF
Explanation:
The blood brain barrier is a barrier formed by brain microvascular endothelial cells, astrocytes and pericytes. Pathogens can cross this barrier by using different mechanisms. The Tumor Necrosis Factor (TNF) is the way gram-negative bacteria cross this mentioned blood-brain barrier.
