Despite their frequency in the intertidal zone, in tide pools, sea urchins can be found at many different depths and in any habitats. They can also be found in nearly any ocean temperature. Sea urchins inhabit the polar seas as well as the warm tropics.
Answer:
Gene mutation:
Gene mutation may be defined as change or alteration in the nucleotide sequence of the gene. DNA replication errors and mutagens are responsible for the gene mutation. A single gene may affected in this mutation. For example: Sickle cell anemia is caused by the replacement of GAG to GUG results in the formation of valine instead of glutamic acid. The shape of RBCs changed from the biconcave to the sickle cell shape.
Chromosome mutation:
Chromosome mutation may be defined as the change or the alteration of chromosome number or structure. Chromosome mutation occurs due to errors during crossing over. The segment of the chromosome may get changed. Large number of genes may get affected. For example: Down syndrome occurs due to the presence of extra chromosome at chromosome 21.
Answer;
It is slowed down dramatically
Explanation;
-The myelin sheath can be described as an insulating layer that is composed of wrappings of the plasma membrane of glial cells that encloses the axons outside the brain and spinal cord. It is a fatty material that coats, protects, and insulates nerves, enabling them to quickly conduct impulses between the brain and different parts of the body.
-In multiple sclerosis the T cells either partially or completely strip the myelin off the fibers, leaving the nerves unprotected and uninsulated. These nerves are not as able to pass messages from the brain to the other body parts. The messages the nerves try to send are delayed or distorted and the messages the brain receives may be misinterpreted.
Answer:
C. "Because you have had one child with Tay-Sachs, you must each carry the allele. Any child you have has a 25% chance of having the disease
Explanation:
Tay-Sachs disease is an autosomal recessive disorder that means a child will acquire the phenotype or we can say disease only when both the alleles which cause disease are present in the child.
Here, in this condition neither parent has Tay-Sachs but they gave birth to a child who is suffering from the disease then it simply means that both the parents are carrier of this disease i.e. they both are heterozygous.
The cross and probability of healthy and diseased child is shown as under:
Mother Father
Parents Tt Tt
/ | | \
Off-springs TT Tt Tt tt
<u>Out of these 4 probable off-springs only 3 with genotype TT, Tt & Tt will be healthy while the 1 with genotype tt will be diseased.</u><u> </u><u>So, the probability of diseased child is 1/4 which is 25%. </u>
Also, the birth of children is an independent event so if one child has already been born with this disease then it doesn't mean that the next 3 children will be healthy for sure i.e. birth of first child cannot influence the next child. In short we can also say that in the next birth, there is still 25% chance of the child being born with this disease because previous birth has nothing to do with next birth.
Answer:
W - Facilitates movement of air by expansion and contraction, X - Traps dust and helps to filter inhaled air, Y - Prevents the wind pipe from collapsing, Z - Help in exchange of gases.
Explanation:
Diaphragm is the muscle that separates the thoracic cavity from the abdomen. The diaphragm is the main muscle of respiration. Contraction of the diaphragm muscle expands the lungs during inspiration when breathing air in. The function of the nasal cavity is to warm, moisturize, and filter air entering the body before it reaches the lungs. Hairs and mucus lining the nasal cavity help to trap dust, mold, pollen and other environmental contaminants before they can reach the inner portions of the body. The trachea, or windpipe, is a 5-inch long tube made of C-shaped hyaline cartilage rings lined with pseudostratified ciliated columnar epithelium. The trachea connects the larynx to the bronchi and allows air to pass through the neck and into the thorax. The rings of cartilage making up the trachea allow it to remain open to air at all times. Gas exchange of oxygen and carbon dioxide takes place in the alveoli. Oxygen from the inhaled air diffuses through the walls of the alveoli and adjacent capillaries into the red blood cells. The oxygen is then carried by the blood to the body tissues.
