Because whales live in the ocean, many people think they are fish. But do you know that whales and dolphins are not fish? They are mammals. People are mammals too. Mammals are the group of animals that breath air using lungs, give birth to live young (rather than laying eggs), and feed their young with mother’s milk. All animals, including people, need oxygen, a chemical found in the air and in water. Fish use their gills to take oxygen from the water that they live in. But people get the oxygen we need by breathing air, using our lungs. Whales and dolphins use their lungs to breathe air also.
That’s one reasons why they come to the surface of the ocean. Sometimes they lie right at the surface of the water, with just a part of their back sticking out. Look closely at a picture of a whale or dolphin; can you see a nose on the whale? You can’t, because whales don’t have noses like you and me. Instead they have a hole – called a “blow hole” – on top of their heads. Sometimes when a whale breathes air out of its blow hole, it shows up as a spray or mist – called a “spout” – that can be seen many miles away. Blow holes are surrounded by muscles that keep the hole closed when the whale or dolphin is under water and open it when the animal is at the surface and needs to breathe.
In fact, some of the animals have two blow holes next to each other and others have only one. So when you see a picture of a whale, see if you can tell the difference. Pilot whales and dolphins have one blow hole; humpbacks, minkes and right whales have two
Answer:
The correct answer is d the positive feed back reduces change in the the system
Explanation:
In an biochemical reaction when the released product stimulate the release and activation of the same product and act together to exibit their biological function, then this type of regulation is called positive feedback.
The positive feed back mechanism leads to increased change in the system that"s why it is named so.
For example during blood clotting platelets molecules are released to form clots to stop bleeding. one activated platelet can stimulates the activity of other platelets which then join together to form a group for generating further blood clots.
The chances that the child will express that trait is 1/4 or 25%. Let the dominant trait be R and the recessive r.
A cross between Rr and Rr would yield RR, Rr, Rr and rr. Only RR would express the trait since its recessive.
Therefore chances =1/4 or 25%
By lesioning the medulla in rats, scientists were able to cause a cessation in breathing. By electrically stimulating the amygdala in rats, scientists were able to trigger aggressive behaviour.
The medulla or medulla oblongata is found in the brainstem and is the structure that regulates autonomic functions of breathing, heart rate and blood pressure. Lesioning is a surgical term which describes the process of injuring a specific part of the brain. Therefore, when the medulla is lesioned, it can no longer function properly and the autonomic process of breathing is interrupted.
The amygdala is comprised of two nuclei within the temporal lobes of the brain and is considered part of the limbic system. Its functions include the processing of memory, decision-making and emotional responses. It has been shown that by electrically stimulating the amygdala in animals, their aggressive behaviour is increased.
Answer:
Explanation:
A. Cancer cells are cancerous because they divide all the time. Normal cells stop dividing once there's enough of them but cancer cells divide when not required as well. Therefore, if Ras is mutated it will always be "on" which means it will activate the pathway which will lead to division of cells i.e. cells divide to multiply their numbers so more cells will be made. Normally, cells only multiply whne there's the growth factor present to activate the whole pathway, but since Ras is mutated it doesnt need the growth factor to activate the pathway, it automatically always activates the pathway even in absence of growth factor.
B. It is highly unlikely that the proposed drug will have a useful effect. This is because mutant Ras protein of this type behaves as though it is constantly "on". Ras acts downstream of the receptor, i.e. first you have the reception of growth factor in receptor, then the ras gets activated. However, the activating mutation makes its effect felt (Ras is activated no matter if there's a growth factor or not), which is why mutant Ras is always active and no longer dependent on the receptor for activation.
Therefore, blocking the ability of the receptor to dimerize and activate Ras will probably not have an effect on cells containing the mutant Ras protein as it does not inhibit the activity of mutated Ras protein.
(Check out the Ras/Ref/MEK/Erk pathway for better understanding of how significant role Ras protein plays in cell proliferation i.e. division)
