Answer:
The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. The basic function of the cell membrane is to protect the cell from its surroundings. It consists of the phospholipid bilayer with embedded proteins.
Answer:
B carbon dioxide
Explanation:
the process uses oxygen and produces carbon dioxide as a waste product.
Answer:
a) Teeth arose from the rough scales of ancestral sharks.
b) Skeletal developments leading to the amphibian movement onto land probably evolved from lobe-finned fishes.
d) The anterior gill arch formed the basis for the evolution of the vertebrate jaw.
Explanation:
The animals we know today have physical characteristics that are evolutionary adaptations of characteristics of their ancestors, which have undergone a series of evolutions and modifications over the years giving rise to new species that have resulted in the species we know today. This process of evolutions and adaptations also happened with the ancestral species of fish, which allowed that today, they had characteristics such as teeth and jaws. Many of these evolutions occurred even in different species, such as the evolution that allowed the amphibians to have a skeleton, which evolved from the spine fins of fish.
Answer:
The correct answer is B. <em>The cells in the outer skin surface appeared flat, whereas the cells in the cross section were not flat.</em>
Explanation:
The epidermis is made up of five cell layers, which have different functions: Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
- <u><em>Stratum basale</em></u> is the <em>innermost germinative, single, basal layer of the epidermis </em>composed of basal cuboidal-shaped cells. These cells are the precursor of keratinocytes, this is why this layer is also called germinativum. In this basal layer, there are also Merkel cells as well as melanocytes.
- <em><u>Stratum spinosum</u></em> refers to the keratinocytes which produce keratin.
- <u><em>Stratum granulosum</em></u>, this is the layer where keratinization begins. Cells produce hard granules that change to keratin and lipids as they ascend.
- <u><em>Stratum lucidum</em></u> is conformed of densely compressed cells, which begins to flatten and appear indistinguishable between each other.
- <u><em>Stratum corneum</em></u> is the most external layer, composed of dead, flattened cells which are released regularly in a process known as desquamation.