Which of the following is a correct statement? [2022]
Cyanobacteria are a group of autotrophic organisms classified under Kingdom Monera.
Bacteria are exclusively heterotrophic organisms.
Slime moulds are saprophytic organisms classified under Kingdom Monera.
Mycoplasma have DNA, ribosome, and cell wall.
(1)
Some of bacteria are autotrophic and vast majority are heterotrophic. Slime moulds are classified under Kingdom Protista. Mycoplasma completely lack a cell wall.
Which of the following organisms are known as chief producers in the oceans? [2018]
Dinoflagellates
Diatoms
Cyanobacteria
Euglenoids
(2)
Diatoms are the most common form of phytoplankton in the ocean. They have the pigment chlorophyll, which helps in photosynthesis. Since they are the primary producers of the aquatic food chain and the marine ecosystem depends on them, they are called chief producers in the oceans.
Ciliates differ from all other protozoans in [2018]
using flagella for locomotion
having a contractile vacuole for removing excess water
using pseudopodia for capturing prey
having two types of nuclei
(4)
Ciliates differ from other protozoans in having two types of nuclei: macronucleus and micronucleus (nuclear dimorphism). E.g., Paramecium has a macronucleus which controls metabolic activities as well as growth and a micronucleus that takes part in reproduction.
Select the wrong statement. [2016]
The walls of diatoms are easily destructible.
'Diatomaceous earth' is formed by the cell walls of diatoms.
Diatoms are chief producers in the oceans.
Diatoms are microscopic and float passively in water.
(1)
Diatoms are marine or freshwater unicellular organisms which have cell walls (frustules) composed of pectin impregnated with silica and consisting of two halves, one overlapping the other. The siliceous frustules of diatoms do not decay easily.
Chrysophytes, Euglenoids, Dinoflagellates, and Slime moulds are included in the Kingdom [2016]
Fungi
Animalia
Monera
Protista
(4)
Protista is a kingdom of unicellular eukaryotic organisms. It includes photosynthetic protists (dinoflagellates, chrysophytes, and euglenoids), consumer-decomposer protists (slime moulds), and protozoan protists.
In which group of organisms the cell walls form two thin overlapping shells which fit together? [2015]
Dinoflagellates
Slime moulds
Chrysophytes
Euglenoids
(3)
Chrysophytes include diatoms and desmids. The body of diatoms is covered by a transparent siliceous shell (silica deposited in the cell wall) known as frustule. The frustule is made of two valves, epitheca and hypotheca, which fit together like a soap box.
