Answer:
double helix
Explanation:
The double helix is a description of the molecular shape of a double-stranded DNA molecule. In 1953, Francis Crick and James Watson first described the molecular structure of DNA, which they called a "double helix," in the journal Nature.
Answer:
Cells from the cheek are a type of epithelial cell, similar to skin. ... They can be seen faintly even at 40x (scanning power), but the most dramatic images are at 400x where the nucleus is clearly visible as a dark spot in the center of the cell.
Explanation:
Keep in mind invertebrates are those who have exoskeletons (outside skeleton) or are hydrostatic (no skeleton). This make up 95% of all animals for example an ant or sponge. For a sponge, all it has is tissues that enable it to allow water to flow out the tops.
2.) Chordata are anything with vertebrates so a simple fish could suffice. THEY HAVE 4 SPECIFIC CHARACTERISTICS: 1.Notochord 2.Dorsal, hollow nerve cord 3.Pharyngeal slits 4.Muscual, an.al tail
3.) This is us, we have thumbs, and vertebrates.
When studying a complex biological phenomenon, it is required to look at the workings of the various systems associated with it. The research is a top-down approach of getting down to the very detail of the cells and molecules taking part in it. Example, a person finds it difficult to digest milk and vomits it on ingestion. As we go a level down, we identify the systems getting affected by the milk. Then, further down, the cells that take in digesting the milk are identified. The enzymes that break down the substances in the milk are identified. The gene regulation of this enzyme (lactase) is studied to check its regulation. This work of doing a top-down approach to find the signalling pathway within the cells to identify the problem with the working of lactase to digest milk, is a necessary approach.
