They are ectotherms.
hope it is helpful to you
Trisomy 21, as illustrated by the karyotype, is caused by nondisjunction. This occurs when chromosomes do not separate properly during meiosis.
Answer is D) nondisjunction
Double fertilization-plants with seeds (flowering plants), two male gametes joining with female gametophyte
Gametophyte generation-both (haploid, sexual stage stage-gametophyte, and the diploid stage that produces spores – sporophyte)
Endosperm formed-plants with seed because it is a tissue formed inside the seed which surrounds the embryo and provides nutrition
Mitosis-both (mitosis occurres in spores)
Spores develop into gametophytes-both but, in seedless plants sporophyte produces spores that will develop into a new organism (multicellular gametophyte) using mitosis, while spores of seed plants are produced internally and develop into more complex structures.
Answer:
When a muscle cell contracts, the myosin heads each produce a single power stroke.
Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, 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 and releases calcium into the sarcolemma. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is liberated. Myofilaments slide impulsed by chemical energy collected in myosin heads, <u>producing a power stroke</u>. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
gene pool? species?
Explanation:
Question is a bit vague hope this helped tho :(
