Answer:b
Explanation:some seeds do not germinate during adverse conditions.this is called dormancy.this may occur due to hard seed coat.this seed coat prevents the entry of water and oxygen which are necessary for the plant to grow and germinate.
Water is a nessesary medium for essential metabolic reactions in the seed.the temperature at which is seed would germinate also varies.
Oxygen is needed for a germinating plant to obtain energy through respiration. The seed coat may also be so tough that they resist growth and expansion from taking place.
Seeds are able to break dormancy on their own.some may need to undergo natural processes that lead to softening.this process may be slow.some others may need heat or certain nutrients.
Germination of seed occurs when the dormant plant has taken in water and oxygen to show high metabolic activities leading to the formation of a seedling.
A result of convergent evolution are the webbed feet of ducks and frogs.
Explanation:
The evolution of the animals, or rather the development of adaptive features, works in very interesting manner. It is very common in nature that animals that are closely related do not share similar characteristics, or the opposite, animals that are not closely related but share similar characteristics. The later case, is referred to as convergent evolution, where totally different animals have developed the same or very similar characteristics in order to be better suited for their environment.
In this case we have the ducks and frogs, and the webbed feet as shared adaptations, or feature. The ducks are birds, while the frogs are amphibians, and their last common ancestor has lived hundreds of millions of years ago. Despite that, both animals have developed webbed feet, and the reason for this has been that both animals have faced the same challenge, swimming and diving, and the webbed feet help them to be much faster and more agile in the water.
Other examples of convergent evolution (in the present and in the past) are:
- Hyena - Tasmanian devil
- Sandy cat - Fenec fox
- Smilodon - Thylacosmilus
- Bats - Birds
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Answer:
Explanation:
When osteocytes were experimentally destroyed, the bones showed a significant increase in bone resorption, decreased bone formation, trabecular bone loss, and loss of response to unloading. ... The osteocyte is an important regulator of bone mass and a key endocrine regulator of phosphate metabolism.
Answer:
Option-D
Explanation:
Parkinson's diseases are a neural disorder which affects the movement of the human body. The disease is caused by the low production or no production of dopamine by the neurons which thus interfere with the impulse transfer and thus movement.
In the given question, the patient with Parkinson's disease is provided with levodopa but no improvement is observed therefore the prescriber must change the drug regimen, for example, the levodopa should be given in combination with carbidopa. These medications enter the blood-brain barrier and get converted to the dopamine.
Thus, Option-D is the correct answer.
