In the nineteenth century, what was known about atoms? A. The atom determines the chemical property of an element.  B. The exact structure of all atoms  C. The half-life of all atoms  D. The number of atoms that exist in the world is increasing.​

Answer:

If both parents do not have sickle-cell anemia, than the possibility is low.

Explanation:

If both parents have the sickle-cell trait, their offspring has a 25 percent chance of getting sickle cell anemia and a 50 percent risk of them having sickle cell trait. Meanwhile, there is also a 25 percent chance of the child not getting it at all.

If one parent has sickle cell anemia and the other has sickle cell trait, then their offspring with have a 50 percent chance of getting sickle cell anemia and a 50 percent chance of getting a sickle cell trait.

When both parents have sickle cell anemia, their child will definitely have it.  

Answer:

No, 0% chance

Explanation:

none of the parents are carriers of this disease, and are homozygous dominant to the normal red blood cells, so they will not inherit this disease

Answer; Radiometric dating

Explanation:How do scientists determine the ages of the rock layers?

The age of rocks is determined by radiometric dating, which looks at the proportion of two different isotopes in a sample. Radioactive isotopes break down in a predictable amount of time, enabling geologists to determine the age of a sample using equipment like this thermal ionization mass spectrometer.

Immotile flowering plants  accomplish fertilization with the help of Insects and other pollen from organisms that carry pollen to other flowers.

Explanation:

• The transfer of pollen from anther to the stigma of flower is called pollination.
• Pollination is of two types: a) Self pollination    b) cross-pollination
• Transfer of  pollen from anther to the stigma of same flower or flower of same plant is called self pollination.
• Transfer of pollen from anther to the stigma of different plant is called Cross-pollination.
• Pollination is the process by which angiosperms carry out sexual reproduction.
• Since, plants are immobile they need some agents for pollination  like, insects birds, wind, water etc

Answer: Cynobacteria

Explanation:

The Precambrian time is the earliest period of earth history. It is preceded by the Cambrian time hence got the name. The earliest living organism in the Precambrian time was the Cynobacteria. It has been found in the fossil record of 3.4 billion years ago. They were the primitive organisms which were capable of conducting photosynthesis and producing oxygen. The abundance of Cynobacteria has resulted in the increase in abundance of oxygen into the atmosphere.