Biology today

(i) Endospermic or albuminous seeds: Endosperm is present and food reserve remains in endosperm, e.g., most monocots and some di ...

are the two major types of cell divisions. The basic stages in both the types of divisions are almost identical. amitoSiS • a ...

• fine radiating microtubules appear around each pair of centrioles to form the astral rays. • a pair of centrioles and as ...

Animal cytokinesis • The spindle gets changed into dense fibrous and vesicular structure on equator called mid body. • In ...

• all those substances or chemicals which affect the cells during mitosis or prevent them from entering into normal mitotic d ...

flow chart : Stages of Meiosis meioSiS i • The heterotypic or reduction division is the first division of meiosis. It starts ...

Zygotene • In cells undergoing meiosis, there are two sets of chromosomes, i.e., the chromosome number is diploid. There are ...

• Crossing over is initiated by enzyme endonuclease which induces nicks (single strand cuts) in each chromatids. • Gaps de ...

metaphase-i • by metaphase I (the second stage of meiosis I), the nuclear envelope has dispersed and the microtubules form a ...

• New nucleolus is formed. The astral rays and spindle fibres disintegrate and disappear. The two daughter nuclei, each conta ...

Fig.:Meiosis inLilium grandiflorum(Lily) Interphase Leptotene Zygotene Pachytene Diplotene Diakinesis Metaphase I (side) Metapha ...

Table : Differences between mitosis and meiosis Mitosis Meiosis Occurs in somatic cells. Limited to the germinal cells. In mito ...

The given figure is a schematic break-up of the phases/stages of cell cycle. Which one of the following is the correct indicati ...

Direction : In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice a ...

Assertion : Sieve tube member and its adjacent companion cells are derived from the same mother cell. Reason : Companion cells ...

Animal Kingdom-X Analysis of various PMTs from 2011-2015 2011 2012 2013 2014 2015 AIPMT/NEET 4 3 8 4 3 AIIMS 2 3 1 6 AMU 2 5 ...

• Fertilisation is internal. • Except egg-laying monotremes, mammals are mostly viviparous giving birth to young ones. • ...

Table : Differences between Prototheria, Metatheria and Eutheria Prototheria Theria Metatheria Eutheria • Ear without pinna ...

Viviparous, (^) − both extinct and living. Their young develops in the uterus, testes extra abdominal, (^) − cloaca is usually a ...

Upper jaw contains two (^) − pairs of incisors while lower jaw has one pair of themPinnae are large (^) − Diastema occur (^) − E ...