Answer:
the answer is D
Amphibians rarely has scales
most amphibians have four limbs and lays their egg in an aquatic environment
Their skins are moist but isn't completely water tight
hope this helps :)
Explanation:
Answer:
Explanation:
The transformation of a zygote into an embryo adheres both to nature and to nurture: not only genetics but also environment determines the outcome. This idea has assumed many forms. A territory in the early sea urchin blastula contains clones of founder cells, and each clone contributes exclusively to one territory (Cameron & Davidson, 1991). Both the lineage of a founder cell, i.e. its nature, and the position of a founder cell, which determines how it is nurtured, contribute to its fate. Fertilisation, the topic of the first Forum, fixes the genes; interblastomere communication, the topic here, regulates gene expression. Blastomeres communicate like any other cell – via ligand-receptor interactions and through gap junctions. Saxe and DeHaan review these mechanisms. The definition of ligands and receptors becomes broadened in this context, and cell adhesions as well as gap junctions enter into the story. In spite of these entanglements, it appears that nature uses the same sorts of mechanisms to get cells to specialise that she uses to keep them talking. Thus, neurons and glial cells signal to one another via glutamate receptors and gap junctions (Nedergaard, 1994). Likewise, we expect neurotransmitters (and neurotransmitter transporters) to help signal differentiation. The biophysicist may ask whether electrical properties also play a role, but that we reserve for another Forum. If gap junctions figure in development as fusion pores that pass small molecules and electrical signals between blastomeres, another parallel suggests itself. Brian Dale asked in the first Forum: How does a spermatozoon activate an oocyte? This question, which concerns gamete communication, has produced two schools of thought and remains controversial (Shilling et al., 1994). Do sperm activate oocytes via contact-mediated mechanisms or through fusionmediated mechanisms? Or do both mechanisms occur, as they appear to in development?
Answer:
The ethics of artificially inserting traits in animals has been in the practice for years in the form of selective breeding, but should scientists really be editing DNA to the extent they are today? I don't believe they should. Life itself should construct itself without us interfering. Making a brand new plant just because it looks nice doesn't account for many factors, including the fact that it could be harmful to nearby plants if pollinated. In addition, generic engineering costs quite a lot of money, which should be used on other more cost effective methods, such as improving agriculture rather than creating a whole new plant that could harm entire crops. Genetic engineering isn't a necessity and humans should not play God with plant and animal life.
DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases. To form a strand of DNA, nucleotides are linked into chains, with the phosphate and sugar groups alternating.
The correct option for above statement is:
c.cell membrane
The cytomembrane (plasma membrane) could be a skinny semi-permeable membrane that surrounds the protoplasm of a cell. Its operate is to shield the integrity of the inside of the cell by permitting sure substances into the cell, whereas keeping different substances out. It conjointly is a base of attachment for the complex body part in some organisms and therefore the cell membrane in others. So the cytomembrane conjointly serves facilitate support the cell and help maintain its form.
