STD 11 - 19. Chemical coordination and integration — BIOLOGY STD 11 Science — Question

$A$. Tetrad formation is seen during Leptotene.

$B$. During Anaphase, the centromeres split and chromatids separate.

$C$. Terminalization takes place during Pachytene.

$D$. Nucleolus, Golgi complex and ER are reformed during Telophase.

$E$. Crossing over takes place between sister chromatids of homologous chromosome. Choose the correct answer from the options given below:

$a -$ Nuclear envelope assembles around chromosomes clusters.

$b -$ Spindle fibers attach to kinetochores of chromosomes.

$c-$ Condensation of chromosomes.

$d -$ Centromeres split and chromatids separate.

$(i)$ Most of them are fresh water organisms found in standing water.

$(ii)$ They have a protein rich layer (called pellicle) which makes their body flexible.

$(iii)$ They have two flagella, a short and a long one.

$(iv)$ Though they are photosynthetic in the presence of sunlight, but in the absence of sunlight they behave like heterotrophs by predating on other smaller organisms. Identify the correct group on the basis of these characters.