Answer:
Plant cells deal with osmosis by being enclosed in a cell wall.
Animal cells use active transport systems to deal with the problem of osmosis.
Fresh water protists have contractile vacuoles to deal with osmosis.
Many bacteria have cell wall to protect them from osmosis.
Explanation:
Plant cells have a rigid cell wall. If a plant cell is places in a place where the conditions are hypotonic, then the cell will tale up water by osmosis but the cell wall will prevent it from bursting. This condition is termed as the cell being 'turgid'.
As animal cells do not have the rigid cell wall, they use the mechanism of active transport system to stop the cell from bursting during osmosis. In this process, ions are moved out of the cell so that the pressure in the cell due to osmosis can be reduced.
Fresh water protists have a structure present in them called as the contractile vacuole. The contractile vacuole has the capability to remove any excess water from the cell as well storing water if there is not enough water.
Bacteria have peptidoglycan cell walls to prevent osmosis.
Distance - an amount of space between two things
Displacement - something that is moved from original place or the area between a object when place in water (volume)
Slope - rise over run or an angle of a line
Sl unit for speed and velocity - meter per second
Sl unit for acceleration - meter per second squared
Answer:
Apoptosis does not involve:
c. lysis of the cell
Explanation:
Apoptosis is a programmed cell death that occurs under normal physiological conditions and in a controlled manner. Normally seen in cell turnover, embryogenesis, also involved in processes of immune, nervous and endocrine systems.
The main morphological and biochemical changes seen during the apoptosis are the fragmentation of DNA by endonucleases, nuclear, chromatin and cytoplasmatic condensation, apoptotic bodies formation (membrane bound-vesicles form of cell parts) and the phagocytosis (digestion) of those bodies by the scavenger cells.
Apoptosis is regulated by cell- signaling pathways, the caspases, a family of cysteine proteases, are the ones involved in the process.
In the process there is no lysis of the cell as this could lead to a inflammatory response (just happens in necrosis) which would affect contiguous cells, and will involve immune cells. In apoptosis there is just a membrane blebbing, but it does not loss its integrity.
Answer:
The correct answers are option A. "tethering proteins to the cell cortex", B. "using barriers such as tight junctions", C. "tethering proteins to the extracellular matrix", D. "forming a covalent linkage with membrane lipids", E. "tethering proteins to the surface of another cell"
Explanation:
According to the fluid-mosaic model, the components of cell membranes are in constant movement forming a barrier to avoid unwanted exterior component internalization and to avoid the loss of precious internal components. This constant movement could cause that proteins move across the plasma membrane. But, this is avoided by several mechanisms including:
A. Tethering proteins to the cell cortex. The cell cortex is a rigid structure made of actin and actomyosin. Proteins found in the plasma membrane are tethered to this structure to restrict their movement.
B. Using barriers such as tight junctions. Tight junctions are barriers found in epithelia made of claudin and occludin proteins. These barriers are impenetrable, which avoid the movement of proteins in the cell membrane.
C. Tethering proteins to the extracellular matrix. The extracellular matrix is made of several proteins and macromolecules that provide a structural and biochemical support to cells that are nearby. Proteins could be tethered to this rigid structure as well.
D. Forming a covalent linkage with membrane lipids. The proteins in the cell membrane that form a covalent linkage with membrane lipids are known as lipid-anchored proteins, or lipid-linked proteins.
E. Tethering proteins to the surface of another cell. When cell-cell communication take place it is possible that proteins in the cell membrane got tethered to the surface of the other cell.
Answer:
Due to no resistance.
Explanation:
Most mosquitoes perish when DDT chemical was sprayed the first time because these mosquitoes are vulnerable to the DDT chemical and there is no resistance present in their body against this chemical. DDT chemical is an insecticide which is used against insects or pests that causes damage to human, organisms and crops. DDT was first synthesized in 1874 by the Austrian chemist named Othmar Zeidler.
