Correct answer is B.
Explanation:
In their nucleus cells contain DNA. The DNA has information about size, shape and function of each cell. When the cell reaches it's full size it stops growing and starts doing whatever it's function is. If more cells are needed then the cell replicates. This explanation excludes answers A and C.
Male and female sexual cells are used to conceive a baby. These cells combine to form a new type of cells. In the first few weeks all types of cells are created. Then the creation of new types of cells stops and existing cells multiply in order to achieve needed number of cells. This explanation excludes answer D.
When we compare an adult person and a baby we can see that, for example, an adult has bigger bones than a baby. This was result of increasing number of existing types of cells without creating any new type.
Answer:
The correct answer will be-
Case I- option-B
Case-II-option-B
Explanation:
A scientific method is the best procedural approach to explain the natural phenomenon. The method includes various steps which begin with the making the observation. The observation leads to the asking the scientific questions which could be answered by proposing a hypothesis.
The hypothesis must be tested through experiments which could prove and disprove the hypothesis and can answer the natural phenomenon.
<u>Case-I</u>
In the given situation of the question in which a person notices or observes the fields of grass and grass and native flower. Since the researcher notices the fields, they are performing the first step of the method that is "making an observation" and thus Option-B is the correct answer.
<u>Case-II</u>
In the situation, which discusses the number of birds in the fields shows the "dependent variables". The dependent variable is the parameter which is studied in the experiments. Since in the given conditions the number of birds is being studied, therefore, Option-B is the correct answer.
Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
