Single celled organisms such as amoebas, especially those that live in fresh water, continually gain water from their surrounding environment by osmosis. This water is pumped into a contractile vacuole which fills with fluid and periodically fuses with the cell membrane, releasing its contents to the exterior. Thus the amount of water actively transported out of the cell is equal to the amount of water entering the cell due to osmosis and there are no variations in the tonicity of the cell. This is homeostasis at a simple level. Without the contractile vacuole, the amoeba would continue to absorb water until its cytoplasmic contents were diluted to such an extent that metabolism no longer occurred and it would die.
Answer:
B. Case-Control
Explanation:
A case-control is a study that compares a group with an outcome of interest (cases) with a group who do not have the outcome (controls). This study aims to looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group and with that to determine the relationship between that risk factor and the outcome.
So in this case, the cases are children with pervasive development disorder and the control is those without the disorders.
These studies are normally observational because no intervention is attempted.
A temperature of absolute zero is the point at which the gas particles stop moving. This corresponds to a temperature of . Particles have no kinetic energy at all so no energy can be removed and the temperature cannot get any lower. With no kinetic energy and now stationary, the particles will exert no pressure either.
Answer:
yes
Explanation:
An analysis of fossil traits indicates that Archaeopteryx is not a bird at all. ... Archaeopteryx seemed to confirm Darwin's theories and has since become a key piece of evidence for the origin of birds, the transitional fossils debate, and confirmation of evolution.
Answer:
1. Obtaining energy
2. responding to a stimulus
3. reproduction
4. excretion
Explanation:
1. All living organisms require energy for their life processes. This energy is derived from food. The food we eat contains biomolecules that store energy. The energy stored by these food molecules is released by a process called RESPIRATION. Image 1 shows a cat trying to obtain energy by feeding. The food will eventually be broken down to release energy.
2. Stimulus is any thing (whether internal or external) that causes a change in an organism. In image 2, a man is responding to a sudden change in his back, which is pain.
3. Reproduction is a characteristics of living organisms that involves the production of young ones. Image 3 depicts two cells undergoing fertilization (fusion of nuclei) to produce a new cell. In turn, the cell divides again to form two gametes. The cycle continues like that.
4. Excretion is the removal of waste products from a cell. According to Image 4, the cell allows a food particle in and releases the waste contents out of the cell.
