Answer:
First, it's important to get clear on the meaning of Homeostasis.
In simple terms, it refers to the capacity of a living thing (plant or animal) to react or behave in such a way that enables it to continue to survive irrespective of changes in its immediate environment.
Explanation:
In humans, the body has a system which reacts to the external stimuli of temprature. When the weather is hot, the brain through a sequence of electrical and chemical signals tells the skin to open up the pore, then we experience venting of sweating which cools the body and regulates internal heat. This is an instance of homeostasis.
This does not mean that the plant or animal is completely immune to such external changes.
In the case of the tomato plant, the hair on the leaves and stem of the plant is an example of Homeostatic responses which have evolved over the years to discourage predators such as the hornworm caterpillar from defoliating the plant.
Cheers!
In an open system such as a campfire, matter can <span>lose particles, gain particles or exchange particles.</span>
<span>a. chemicals produced by neurons that function as hormones—neurohormones
b. chemicals that act locally on nearby cells—paracrine factors
c. chemicals secreted by presynaptic terminal—neurotransmiters
d. influences same cell type from which it is secreted—autocrine agent
e. chemical secreted into the blood by specialized cells; travels some distance to target tissues—endocrine hormones</span>
Answer:
Explanation:
Proteins in the plasma membrane have several functions based on their components, location etc. For instance, if the protein transcends the entire plasma membrane it could be a transport protein, responsible for the import and export of certain molecules between the cell and the extracellular matrix (ECM). If the proteins are resting at the surface of the cell, facing the ECM, their role could be to detect components in the ECM, relaying a series of messages back to the nucleus so that the cell can ‘decide’ what it should do with this information (is it being told it should undergo apoptosis, should it begin to divide, should it migrate?). As well as this, it could be involved in the detection of foreign bodies such as pathogens. This is an extremely job for these proteins because if the cell does come in contact with a pathogen, the cell can use these proteins to engulf the pathogen and through a series of steps, present the antigen on their major histocompatibility complexes (either 1 or 2 depending on the cell type) or HLA’s for human cells. Thus it can be concluded that protein functions vary widely in the plasma membrane and due to the vast number of proteins that can be found there, it’s difficult to narrow down the exact main of functions of all these proteins put together.