B positive patients can receive blood from B positive, B negative, O positive and O negative donors.
Answer:
Dermis.
Explanation:
The skin is the outer most protective layer that differ in structure and composition of the vertebrates. The main function of skin is the regualtion, sensation and protection of the organism.
The skin is divided into different layer : epidermis, basement membrane dermis, and subcutaneous tissue. Only the dermis layer contains the living cells that are highly vascularized and present beneath the hypodermis. Dermis layer protect the body from the stress and strain.
Thus, the correct answer is option (2).
Crossing over happens in Meiosis 1 only. In Prophase 1 a cells chromatin (chromatin = chromosomes that have not condensed yet) condense and pair up forming homologous chromosomes (paired = XX (2 chromosomes together)). When this happens segments/ alleles of the chromosomes pairing up swap over. This creates genetic diversity as each chromosome is different, it has parts from its pair. This leaves every chromosome unique and individual.
I hope this helps, sorry some of the vocab is rather technical. By the way I would suggest watching the
'Crash Course: Meiosis' on YouTube, this really helped me when I was learning this topic. :D
Explanation:
1.The Moon has phases because it orbits Earth, which causes the portion we see illuminated to change. The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle (from new Moon to new Moon) is 29.5 days. The Moon spends the extra 2.2 days "catching up" because Earth travels about 45 million miles around the Sun during the time the Moon completes one orbit around Earth.
2.
An eclipse is the result of the total or partial masking of a celestial body by another along an observer's line of sight. Solar eclipses result from the Moon blocking the Sun relative to the Earth; thus Earth, Moon and Sun all lie on a line. Lunar eclipses work the same way in a different order: Moon, Earth and Sun all on a line. In this case the Earth's shadow hides the Moon from view.Lunar and solar eclipses occur with about equal frequency. Lunar eclipses are more widely visible because Earth casts a much larger shadow on the Moon during a lunar eclipse than the Moon casts on Earth during a solar eclipse. As a result, you are more likely to see a lunar eclipse than a solar eclipse.
3.Why Do We have Seasons?
As the earth spins on its axis, producing night and day, it also moves about the sun in an elliptical (elongated circle) orbit that requires about 365 1/4 days to complete. The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons. When the earth's axis points towards the sun, it is summer for that hemisphere. When the earth's axis points away, winter can be expected. Since the tilt of the axis is 23 1/2 degrees, the North Pole never points directly at the Sun, but on the summer solstice it points as close as it can, and on the winter solstice as far as it can.
Why Do the Seasons Change on Earth?
Two things cause the seasons to change. First, the Earth moves around the Sun. Second, the Earth has a tilted axis of rotation.
The Earth spins around an axis. This imaginary line extends from the South Pole to the North Pole. But the Earth’s axis is not vertical. It’s actually tilted at an angle of 23.5°. The planet is always tilted in the same direction as it orbits the Sun.
