Biology · Biological Classification · NEET
NCERT gives three simple points. (1) Bacteria reproduce MAINLY by fission. Fission means one bacterial cell divides into two equal cells. (2) Sometimes, under unfavourable conditions, they produce spores. (3) They also reproduce by a sort of sexual reproduction, using a primitive type of DNA transfer from one bacterium to another. That is all NCERT says here, so learn these three points exactly.
Binary fission is ASEXUAL. Only one parent is needed. The single cell copies its DNA and splits into two identical daughter cells. There is no fusion of gametes and no mixing of DNA from two different parents. This is the main and fastest way bacteria multiply.
Not in the full sense that plants and animals do. NCERT calls it 'a sort of sexual reproduction' and 'a primitive type of DNA transfer'. Two bacteria come close and one passes a piece of DNA to the other. No gametes fuse and no zygote forms, so it is only sexual-LIKE. It is important because it mixes genes and creates variation.
Bacterial spores are mainly for SURVIVAL, not for multiplying in numbers. NCERT says spores are made 'under unfavourable conditions', for example when there is no food, no water, or high heat. The spore is a tough, resting stage. When good conditions return, the spore grows back into a normal bacterium. So a spore helps the bacterium wait out bad times, not increase its count.
Binary fission is the normal, everyday way bacteria multiply and increase in number, done in good conditions. Spore formation happens only in bad conditions and produces a single tough resting cell for survival, not many new cells. Fission = grow the population; spore = survive the crisis. NEET often tests this exact difference.
Conjugation is the common name for the DNA transfer that NCERT describes as 'a primitive type of DNA transfer from one bacterium to the other'. One bacterium acts as a donor and passes DNA to a recipient bacterium. For Class 11 NEET, just remember it is the 'sexual-like' method that transfers DNA and creates variation. The detailed mechanism is studied later in higher classes.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Binary fission. One cell copies its DNA and splits into two equal daughter cells. It is asexual and very fast, which is why bacteria multiply quickly.
No. A bacterial spore (endospore) is mainly a survival/resting stage made in bad conditions, and usually one bacterium makes one spore. Fungal spores are true reproductive units used to make many new individuals. Do not mix these up in NEET.
No. In bacterial DNA transfer no gametes fuse and no zygote is formed. That is why NCERT calls it only 'a sort of' or 'primitive' sexual reproduction, not real sexual reproduction.
Fast fission plus DNA transfer means bacteria multiply quickly and gain new gene combinations. This links to variation, antibiotic resistance, and disease spread, which are useful ideas across your biology syllabus.
