In a comparison of birds and mammals, having four appendages is <span>a shared ancestral character</span>
Answer: skeletal system
Explanation: osteoarthritis affects the cartilages of Bones.cartilages is a flexible connective tissue ,in a joint that covers the surface of the bones in the joint.it also cushions the bones from impact.
During osteoarthritis,the cartilages wears out and causes the bones in the joint to rub against each other causing swollen joints, painful joints and stiffness of joints
It occurs in joints of the knees,hips,fingers and toes.
Maintaining acidity- <span>In case the pH in the environment drops a lot (becomes very acidic), there is a flux of H ions from the cell's cytoplasm into the cell's vacuole thereby increasing acidity to required level and thus maintaining the </span><span>specific pH </span><span>in the cells internal environment as well.
Turgidity- </span><span>Vacuoles regulate the turgidity by regulating the amount of water inside the cell. </span>
cell has excessive water:<span> vacuole absorbs the water and then diffuses it out of the cell.</span>
cell lacks water<span>: water from the vacuole gets passed back into the cell thereby maintaining turgidity.
And here's a video </span>https://youtu.be/3tqjITi8S8s
The answer is D. The dark mice could not camouflage on the white beach sand hence were more conspicuous. Therefore, the Predators were able to easily spot them and prey on them. Therefore, the phenotype of dark mice reduced in the population since most mice were not able to reach maturity and pass down their traits. The allele for white fur, therefore, increased in the population. This is the process of natural selection at work.