Why is it easier to classify protists by methods of nutrition and movement than by habitat (where
they live)?
Solution
Answer:
The protists are multicellular and single-celled and consume their nutrition by ingesting food
through \"phagocytosis\" or endocytosis. Varieties of protists are classified as per movement
rather than habitat because several protist are motile due to presence of cilia, flagella, or
pseudopodia and autotrophic or heterotrophic in nutrition. These protists are pertaining different
environments becuase csoem of them live as endosymbionts in internal environment sof other
hosts whereas some of them do live in terrestrial & aquatic environments so that difficult to
classify on the basis of habitat
Protsist have three modes of locomotion to produce locomotion in water. These are
1. Pseudopodial Locomotion: Locomotion in water using axopodia
2. Flagellar Locomotion: Motility using flagella
3. Ciliary Locomotion: motility using cilia
4. Wriggling Locomotion
Protists niches- photoautotrophic: pennate diatoms, euglena (motile), pediastrium (colonial &
non motile), scenedesmud
These protists are photoautotrophic as they possess chloroplasts consist of pyrenoids and these
pyrenoids are going to be used for the synthesis of paramylon. These are going to the influence
the metabolic activity of each species physically and chemically factors influencing in each of
the organisms. This starch constituent used for energy production for Euglena during light
deprived condition. Even though there are no specific ancestor features between green algae and
Euglena, oscilaltoria algae, both species contain pyrenoids. Some of these are with flagella and
possesses both plant and animal features.
Why would you not expect water to move easily through a membrane Ho.pdf
1. Why would you not expect water to move easily through a membrane? How do they do it?
What does it mean that phospholipids are amphipathic?
Solution
Cell membrane comprise of phosphipid bilayers. Phospholipids are polar at one end (that means
they are hydrophilic or water loving at one end) and non polar (that menas hydrophobic or water
fearing) at the other end. This bipolar nature of phospholipids is called as amphipathic.A
phopspholopid has a glycerol molecule attached at its head with two long fatty acid hydrocarbon
chains. Long hydrocarbon tail of the lipid part has non-polar bonds and is hydrophobic in nature
whereas head part of it, where phosphate group is attached is hydrophilic in nature. These
amphiphatic molecule comes together to form bilayer structures of cell membrane.
This phopholipids are thus being hydrophobic at one end form a barrier for water to enter the
cell. Majorly water passes in the cell through special channel proteins called aquaporins.
Aquaporins act as transmembrane proteins which act as gated water channels thereby facilitating
the rapid transport of water acoss the cell membrane, even against the concentration
gradient.Only a small amount can pass through the phospholipid bilayer by the process of
osmosis (along the concentration gradient).
