Crossing over occurs at the four-strand stage when two homologous chromosomes, each consisting of a pair of sister chromatids, are paired. Each crossover involves just two of the four strands and generates two recombinant strands.
Hope this helps!
Just took the quick check 100%!! Lets keep it 100.
1. B (Blood flows through a system of blood vessels and throughout the body)
2.C (I<span>n blood vessels and sinuses)
3.B (</span><span>Oysters do not move around, but squid are very active)
4.D (</span><span>It is difficult for single pump to force blood through the entire system of a large animal)
5.A (</span><span>Exchanging carbon dioxide for oxygen from the air)</span>
Lumbar region refers to the lower back or lower spine.
important muscles of the lumbar spines are:
1) multifidus - stabilizes and rotates the lumbar spine
2) longissimus
3) spinalis
lower back pain are caused by improper posture, compression fracture, muscle injuries, fractured vertebrae, spinal stenosis, osteoarthritis, herniated disc.
<span>2 ATP molecules be invested in the system. </span>
