For centuries scientists thought the Universe always existed in a largely unchanged form, run like clockwork thanks to the laws of physics. But a Belgian priest and scientist called George Lemaitre put forward another idea. In 1927, he proposed that the Universe began as a large, pregnant and primeval atom, exploding and sending out the smaller atoms that we see today.
His idea went largely unnoticed. But in 1929 astronomer Edwin Hubble discovered that the Universe isn’t static but is in fact expanding. If so, some scientists reasoned that if you rewound the Universe's life then at some point it should have existed as a tiny, dense point. Critics dismissed this: the celebrated astronomer Fred Hoyle sarcastically called this concept the “Big Bang Theory"
Answer: A normal female karyotype is written 46, XX, and a normal male karyotype is written 46, XY.
Explanation:
Answer:
A. True
Explanation:
Hemoglobin is a protein and has two distinct types of polypeptide chains. These are called the alpha and beta subunits. The gene that code for the beta chain undergoes a mutation in a single base that causes sickle cell anemia. Here, adenine base in the genetic code for glutamic acid is substituted with a thymine base.
The genetic code for glutamic acid in the beta chain gene is GAG. The "A" is replaced with "T" and the new code "GTG" codes for valine. Therefore, the mutated hemoglobin has valine in place of glutamic acid. This makes these mutated protein molecules to form aggregates resulting in a change in the shape of RBCs carrying them.
Answer: CHANNEL PROTEINS provide openings in the plasma membrane for substances to flow through without changing structure, and CARRIER PROTEINS allow passage of substances through the plasma membrane after undergoing a subtle change in shape.
Explanation: They are described thus:
A channel protein is a protein that allows the transport of specific substances across a cell membrane.
Carrier proteins are proteins that carry substances from one side of a biological membrane to the other. Many carrier proteins are found in a cell’s membrane, though they may also be found in the membranes of internal organelles such as the mitochondria, chloroplasts, nucleolus, and others.
The answer is C. The brain stem controls blood circulation.
