Answer:
A. Lancelet
B. All chordates
Explanation:
A. Dorsal nerve chord is the only <u>unique feature</u> among all members of <u>phylum chordata</u> (mainly found in subphylum Vertebrata). In the given list, only lacelet is the Chordate whereas <u>snail belongs to phylum Mollusca</u>, <u>grasshopper belongs to Arthropda</u>, and <u>jellyfish belongs to Cnidaria</u>. Dorsal nerve cord runs along the length of organism's body.
B. <u>Gill slits</u> are <u>opening structures</u> to gills through which water passes from pharynx/throat to exterior. Their main purpose is to help filter the food particles available in surrounding water. Although they are typical for amphibians and fishes, chordates also possess gill slits at embryonic stages.
Answer:
The correct option is B. Activation energy
Explanation:
The activation energy is usually used to designate the minimum energy necessary for a given chemical reaction to occur, that is, the basic requirement for the reaction to proceed.
For a reaction to occur between two molecules, they must collide in the correct orientation and have a minimum amount of energy. As the molecules approach, their electron clouds are rejected. This requires energy (activation energy) and comes from the heat of the system, that, is, from translational, vibrational energy, etc of each molecule. If the energy is sufficient, the repulsion is overcome and the molecules are close enough for a rearrangement of the bonds of the molecules.
The concept of Activation energy was introduced by Arrhenius in 1889. Arrhenius suggested that molecules must prossess a minimum amount of energy to react. That energy comes from the kinetic energy of the clliding molecules. Kinetic energy serves to cause reactions, but if the molecules move very slowly, the molecules will only bounce when they collide with other molecules and the reaction does not happen. In order for the molecules to react, they must have a total kinetic energy that is equal to or greater than a certain minimum value of energy called activation energy.
The purpose of an indicator is to test how acidic or basic something is.
Answer:
a gradual increase in the overall temperature of the earth's atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, chlorofluorocarbons, and other pollutants.