1. Cell transport
The movement of materials into and out of cells influences the internal concentrations of the molecules. So, you can see
that what goes in or out will have a profound effect on the ability of cells to function properly. The ability of cells to
move materials in and out efficiently can determine whether they will live or die. How do cells control these
movements? They do it by both passive and active transport. We will examine these processes in this section. Before we
begin, however, I want to stress the importance of the plasma membrane that surrounds cells. To get in or out of a cell,
material must pass through this membrane. It is the membrane that is the gatekeeper of cells.
Exocytosis
In exocytosis wastes and cell products are packaged by Golgi apparatus in sacs called Golgi vesicles. Gogi vesicles fuse
with the cell membrane and the materials in the vesicles are secreted out of the cell.
Endocytosis
The cell membrane surrounds desirable macromolecules outside the cell. The cell pinches off a saclike portion of its
outer membrane to form a tiny new vesicle .the vesicle moves into the cell where it releases its contents into the
cytoplasm.
Pinocytosis
In Pinocytosis the cell membrane encloses a droplet of fluid and its solutes and brings the droplet into the cell.
Phagocytosis
In Phagocytosis the cell engulfs a food particle . The vesicle containing food then fuses with a lysosome carrying
digestive enzymes
.Four types of animal tissue?
Zoology or Animal Biology Questions
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Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of
similar cells and from the same origin, that together carry out a specific function. These are called tissues because of
their identical functioning. Organs are then formed by the functional grouping together of multiple tissues.
Animal tissues
Animal tissues can be grouped into four basic types: connective, muscle, nervous, and epithelial. Multiple tissue types
comprise organs and body structures. While all animals can generally be considered to contain the four tissue types, the
manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells
comprising a particular tissue type may differ developmentally for different classifications of animals.
The epithelium in all animals is derived from the ectoderm and endoderm with a small contribution from the
mesoderm, forming the endothelium, a specialized type of epithelium that comprises the vasculature. By contrast, a
true epithelial tissue is present only in a single layer of cells held together via occluding junctions called tight junctions,
to create a selectively permeable barrier. This tissue covers all organismal surfaces that come in contact with the
external environment such as the skin, the airways, and the digestive tract. It serves functions of protection, secretion,
and absorption, and is separated from other tissues below by a basal lamina.
Connective tissue
Connective tissues are fibrous tissues. They are made up of cells separated by non-living material, which is called
extracellular matrix. Connective tissue gives shape to organs and holds them in place. Both blood and bone are examples

2. of connective tissue. As the name. It supports and binds other tissues. Unlike epithelial tissue, connective tissue typically
has cells scattered throughout an extracellular matrix2.
Muscle cells form the active contractile tissue of the body known as muscle tissue or muscular tissue. Muscle tissue
functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle tissue is
separated into three distinct categories: visceral or smooth muscle, which is found in the inner linings of organs; skeletal
muscle, in which is found attached to bone providing for gross movement; and cardiac muscle which is found in the
heart, allowing it to contract and pump blood throughout an organism.
Nervous tissue
Cells comprising the central nervous system and peripheral nervous system are classified as neural tissue. In the central
nervous system, neural tissue forms the brain and spinal cord and, in the peripheral nervous system forms the cranial
nerves and spinal nerves, inclusive of the motor neurons. Nervous tissue functions to transmit messages in form of
impulse.
Epithelial tissue
The epithelial tissues are formed by cells that cover the organ surfaces such as the surface of the skin, the airways, the
reproductive tract, and the inner lining of the digestive tract. The cells comprising an epithelial layer are linked via semi-
permeable, tight junctions; hence, this tissue provides a barrier between the external environment and the organ it
covers. In addition to this protective function, epithelial tissue may also be specialized to function in secretion and
absorption. Epithelial tissue helps to protect organisms from microorganisms, injury, and fluid loss. Functions:
*the cell of the body surface form the outer layer of skin.
*inside the body,epithelial cells forms lining of mouth & alimentary canal & protect these organ.
*epithelial tissues help in absorption of water & nutrient.
*epithelial tissues help in elimination of waste product.
The different types of epithelial tissues are as follows:
Squamous epithelium,
Cuboidal epithelium,
Columnar epithelium,
Glandular epithelium,
Ciliated epithelium.