Q.(16) Give two differences between a zygote and a foetus. (2)
Q.(17) What are displacement reactions? Explain with example. (2)
Q.(18) What are the major groups of microorganisms? Write with example. (2)
Q.(19) Define the process of carbonization? (2)
Q.(20) Why chloroplast are found in plants? (2)
Q.(21) Make a well labelled diagram of Plant cell. (do not use any type of pen)
Answers
Answer:
Q. 16
Zygote
It is formed by the fusion of the nuclei of the sperm and egg. It is a unicellular structure. Produced after the processes of fertilization.In Zygote well-described body are absent.
Foetus
It is the stage of the embryo which nearly resembles a human being. It is a multicellular structure.Produced after the processes of cell division and cell labour division.In Foetus well-described body parts are present.
Q. 17
In a displacement reaction more reactive element displaces a less reactive element to form a compound. displacement reaction can be seen in metals and non-metals both.
Examples: Zinc displaces iron ions from iron sulphate solution.
nickle displaces copper from copper nitrate solution.
Q. 18
major groups of microorganisms:
Bacteria :They are single-celled disease-causing micro-organisms. They can be spiral or rod-shaped.
Fungi :They are mostly multicellular disease-causing microbes. Bread moulds are common examples of fungi.
Protozoa: They mainly include organisms such as Amoeba, Plasmodium, etc. They can be unicellular or multicellular.
Virus :Viruses are disease-causing microbes that reproduce only inside the host organism.
Algae :They include multicellular, photosynthetic organisms such as Spirogyra, Chlamydomonas, etc.
Q. 19
It is defined as the conversion of organic matter into carbon or the residues containing carbon through the process of pyrolysis or destructive distillation.
Q.20
Chloroplasts are found in plant cells only because chloroplasts contain chlorophyll which is essential for photosynthesis.
Chlorophyll traps sunlight and uses it to prepare food for plants by the process of photosynthesis.