The Precambrian time refers to the time 4.5 billion to 542 millions year ago. This period is characterized by having reduced atmosphere and included reduced compounds. Scientists believed that atmosphere at that time was devoid of free oxygen and CO2 was present in excess. Before the complex life evolved on the Earth, the Precambrian Earth's ocean contained dissolved carbon dioxide.
Sorry if I’m wrong but I believe it’s the cardiovascular and lymphatic system
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Answer: More than 90% of measles infections occurs in children under 15 years old.
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I believe the answer is B. Hope I help! Sorry if not. ):)
Answer:
The correct answer would be - 50%.
Explanation:
Hemophilia is a sex-linked recessive disorder that takes place in males more than in females as females have two X chromosomes so if one is affected other still able to make clotting factors but in males, there are only one x chromosome.
If a hemophilic man XhY marries with a carrier women XHXh then the chances of their son for normal blooding would be :
Gametes:
Male: Xh and Y
Female: XH and Xh
Then cross:
Xh Y
XH XHXh XHY
(carrier daughter) (normal son)
Xh XhXh XhY
(hemophilic daughter) (hemophilic son)
Thus, the chances of normal son is 50% among sons
