Phylogeny
uses communal ancestry to group organisms and further nest them into bigger and
bigger groups. This is also a study of evolutionary relationships among
organisms. Visible characteristics such as anatomical and behavioral traits, as
well as biochemical (enzymes, proteins, pigments, etc.) and genetic traits
(nucleotide sequences) that need more modern techniques to detect.
Answer:
What does a linear velocity graph tell us?
The principle is that the slope of the line on a velocity-time graph reveals useful information about the acceleration of the object. If the acceleration is zero, then the slope is zero (i.e., a horizontal line). If the acceleration is positive, then the slope is positive (i.e., an upward sloping line).
What is an acceleration time graph?
A graph that shows acceleration plotted against time for a particle moving in a straight line. ... The acceleration-time graph is the graph y=a(t), where the t-axis is horizontal and the y-axis is vertical with the positive direction upwards.
graph shows changes in velocity of a moving object over time. The slope of a velocity-time graph represents acceleration of the moving object.
Explanation:
<em>zygote</em> is the diploid cell that results from the fertilization between an egg and sperm
<em>sperm</em> is the male reproductive cell that is responsible for a baby to born
Answer:
In muscles contraction the correct order of the steps are: A (Nerve impulse reaches the muscle), B (Action potential travels down T-tubules), C (Calcium binds to troponin), D (Tropomyosin moves).
Explanation:
Skeletal muscle contractions are based on different physiological and biochemical phenomena that happen in every cell. These phenomena are due to stimulation produced by somatic motor neurons, which axons get in contact with muscle fibers through a neuromuscular synapse. In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When an action potential is originated in the central nervous system, it travels to the somatic motor neuron membrane: the muscle fiber, and activates the calcium channels releasing it in the neuron. Calcium makes vesicles to fuse with the membrane and release the neurotransmitter named acetylcholine (Ach) into the synaptic space in the juncture. Then, Ach binds to its receptors on the skeletal muscle fiber. This causes the ion channels to open, and positively charged sodium ions cross the membrane to get into the muscle fiber (sarcoplasm) and potassium get out. The difference in charges caused by the migration of sodium and potassium makes the muscle fiber membrane to become more positively charged (depolarized). The action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane, that make the calcium be released into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin binds to the uncovered actin-binding sites, and while doing it ATP is transformed into ADP and inorganic phosphate. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
