Solution:
Oxygen crosses a plasma membrane by diffusion.

Solution:
Animals or organism floating on the surface of water is plankton.

Solution:
The zygosity of F1 generation can be checked by test cross method. In a test cross : The organism with the dominant trait is always crossed with an organism with the recessive trait. If any offspring show the recessive trait, the unknown genotype is heterozygous. If all the offspring have the dominant trait, the unknown genotype is homozygous dominant. Large numbers of offspring are needed for reliable results.

Solution:
Deficiency of iodine causes goitre.

Solution:
The innermost part of a flower is known as Stamens.

Solution:
Cytoplasm consists of an aqueous ground substance, the cytosol, containing a variety of cell organelles and other inclusions such as insoluble waste and storage products (starch, glycogen, lipid, etc.)

Solution:
Litmus paper is an acid/base indicator that changes color to identify bases and acids. Litmus is a dye made from naturally occurring substances, including lichens (fungi)– the most commonly used of which is the species roccella tinctoria.