abida Archive

OBJECTIVES

Multiple Choice Questions MCQs Four options are given at the end of each statement. You should encircle one option from them. Which of the following compound is’absent in plasma membrane? (a) Proteins (b) Carbohydrates (c) Cholesterol                      (d) wax The word mosaic is used for:

MODEL SUBJECTIVE QUESTION

Describe the fluid mosaic model of cell membrane. Describe different movements across the cell membrane. Write note on ribosomes. Write note on endoplasmic reticulum. Describe structure and function of Golgi apparatus. Discuss structure and function of Lysosomes. Describe structure and functions of mitochondria. Write

ORGANS AND ORGAN SYSTEM

Organ The group of different tissues performing same function is called organs. Different tissues are organized into the organs except simplest animals (sponges and cnidarians). Some organs have their tissue layers. For example, the stomach has four major layers. The lumen is lined by

Connective Tissues

The tissue with loose arrangement of cells and the cells are scattered in an extracellular matrix are called connective tissue This non living matrix consists of a web of fibers. These fibers are embedded in a homogenous ground substance. This substance may be liquid,

TISSUES

The group of similar cells which performs same functions is called tissue. There are four types of tissues: epithelial tissues, connective tissues, muscles tissues and nerve tissues. Epithelial tissues The sheets of tightly packed cells are called epithelial tissues. Epithelial tissue covers the outside

NUCLEUS

Nucleus contains most of the genes that control the cell. It is the most conspicuous organelle in the eukaryotic cell. Its average diameter is about 5. It performs two major functions: The information of DNA of nucleus is transcribed into RNA. This RNA is

VACOULES AND VESICLES

Vacuoles and vesicles are membrane-enclosed sacs within the cell. But vacuoles are larger than vesicles. Vacuoles have various functions. They form food by phagocytosis. Many freshwater protists have contractile vacuoles These vacuoles pump excess water out of cell. Certain vacuoles are filled with pigments.

CENTRIOLES AND MICROTUBULE ORGANIZING CENTERS

Microtubule-organizing centers The specialized non membranous regions of cytoplasm near the nucleus are the microtubule-organizing centers. These centers contain dense material. This material gives rise to a large number of microtubules. These micotubules have different functions in the cytoskeleton. Centrioles One type of center

THE CYTOSKELETON

The cytoskeleton is a network of fibers suspended through the cytoplasm. There are three fibers in the cytoskeleton. These are microtubuies, microfilaments and intermediate filaments. Functions of Cytoskeleton – The cytoskeleton performs following functions in the organisms: They give mechanical support to the cell

MITOCHONDRIA

Mitochondria are commonly called as power house of the cell. They provide energy transuding system. This system is used to change the food into chemical energy by oxidative phosphorylation ATP is synthesized during oxidative phosphorylation. Structure of Mitochondria Mitochondria are rod shaped. Their diameter