Which of the following is incorrect about Cynobacteria?
Explanation:
The incorrect statement is option 2. Cyanobacteria are photoautotrophs and carry out photosynthesis. Many cyanobacteria form specialized cells called heterocysts for nitrogen fixation, so they do have heterocysts in several species. They often form blooms in polluted or nutrient-rich water bodies, and they contain chlorophyll a, along with other pigments, which is similar to green plants.
๐ง Did You Know?
Cyanobacteria are sometimes called blue-green algae, but they are bacteria, not true algae. They play a key role in nitrogen cycling due to heterocysts in some species.
๐ก NCERT Memory Line:
Cyanobacteria are photosynthetic and may fix nitrogen in heterocysts; they form blooms in polluted waters and possess chlorophyll a similar to green plants.
The size of Pleuropneumonia - like Organism (PPLO) is:
Explanation:
PPLO stands for Pleuropneumonia-Like Organism, which is the organism Mycoplasma pneumoniae. According to NCERT biology, PPLOs are very small, about 0.1 ฮผm in size, much smaller than many bacteria. Thus the correct size is 0.1 ฮผm (option 4).
๐ง Did You Know?
PPLOs lack a cell wall and have a flexible membrane, which helps them survive as small organisms in various environments.
๐ก NCERT Memory Line:
PPLO organisms are extremely small, around 0.1 ฮผm, illustrating how some pathogens can be much smaller than typical bacteria.
Which of the following statements about inclusion
bodies is incorrect ?
Explanation:
Inclusion bodies are reserve materials (like glycogen, lipids, pigments) that lie free in the cytoplasm and are not bounded by a membrane. They do not participate in the ingestion of food particles. Therefore, statement 2 is incorrect.
๐ง Did You Know?
NCERT describes inclusion bodies as reserve deposits in the cytoplasm, formed when resources are stored for later use.
๐ก NCERT Memory Line:
Inclusion bodies: reserve materials in the cytoplasm, often not membrane-bound.
Match the following group of organisms with their
respective distinctive characteristics and select the correct option :
Organisms
Characteristics
(A)Platyhelminthes
(I)Cylindrical body with no segmentation
(B)Echinoderms
(II)Warm blooded
animals with direct development
(C)Hemichordates
(III)Bilateral symmetry with incomplete
digestive system
(D)Aves
(IV)Radial symmetry with indirect
development
Choose the correct answer from the options given below:
Explanation:
Matchings as per NCERT:
- Platyhelminthes (A) have bilateral symmetry and are unsegmented with an incomplete digestive system (only one opening). => (III)
- Echinoderms (B) show radial symmetry as adults and have indirect development (larval stage). => (IV)
- Hemichordates (C) are worm-like, unsegmented (cylindrical body, no segmentation) organisms. => (I)
- Aves (D) are warm-blooded and show direct development (hatching resembles the adult). => (II)
Thus the correct pairing is A-III, B-IV, C-I, D-II. The other options mismatch these standard NCERT characteristics.
๐ง Did You Know?
Hemichordates and Echinoderms are considered deuterostomes, like chordates, in embryology.
Which of the following statements are true for
the phylum-Chordata?
(A) In Urochordata notochord extends from head to tail and it is present throughout their life.
(B) In Vertebrata notochord is present during the embryonic period only.
(C) Central nervous system is dorsal and hollow.
(D) Chordata is divided into 3 subphyla : Hemichordata, Tunicata and Cephalochordata.
