Question

1. Give an overview of the major forms of life. Explain why organisms do not fall neatly into discrete categories and give examples of major transitions.

2. Cells need to carefully modulate what molecules can pass into and out of the cell. What barriers do bacteria have to maintain a constant internal environment? Describe various transport mechanisms and their characteristics.

Answer 1

# Major forms of life are

Bacteria (Do not have definite nucleus)

Archaea ( Unicellular prokaryote lives in extreme conditions)

Protists (Unicellular protozoans)

Fungi (saprophytic eukaryotes)

Plant (Autotrophic eukaryotes)

Animalia (Heterotrophic eukaryotes)

Due the complete change in the mode of life and complexity, they do not fall on discrete category.

# Plasma membrane and the cell wall are the barriers hold by bacteria to maitain a constant environment inside the cell.

Plasma membrane is selectively permeable. It does not allow all the molecules inside.

- Types of transportation

Active transport ( Needs ATP and its against concentration gradient).

Pssive transport (Does not need ATP and it is according to the concentration gradient)

facilitated transport (Needs a specilised transporter molecule)

Diffusion (Simple movement of molecules according to the concentration gradient)