Cell Biology Online Test 7th Science Lesson 10 Questions in English

Explanation

Bacteria are micro-organisms that can be seen only under microscope and not seen through naked
eyes. Salmonella species is a Bacteria that can cause food-borne infection

Explanation

The basic functional unit of an organism is called, a cell. Structure of a cell represent the
arrangement of parts or organelles in a cell. Function is the activity of each part or organelle in a
cell. Cells are the basic building blocks of an organism.

Explanation

Some simple organisms, are made up of only one cell. They are called unicellular organisms, which
can be seen with the help of a microscope. There are many single – celled microscopic organisms.

Explanation

Chlamydomonas and an Amoeba, a single-celled organism which carryout entire functions. The
body of all organisms are made up of tiny building blocks called, cells. Bacteria are also one celled
unicellular organism.

Explanation

The cells are organized into tissues, organs and organ systems in a multicellular organism.
Macroscopic organisms are visible and consists of many cells. The body of macroscopic organisms
involves various functions.

Explanation

Many cells function together to form tissues, different tissues combined together to form an organ
and different organs to form an organ system, which leads to form an organ. Many types of organ systems function together in a body, e.g. respiratory system, digestive system, excretory system,
circulatory system etc.

Explanation

Many organs together form an organ system, which is concerned with a specific function. For
example, Respiratory system, which has organs like nostrils, nasal chamber, wind pipe and lungs
that helps in the process of respiration

Explanation

In a plant, the root system consists of primary root, secondary root and tertiary root, which does
the function of conduction of water, mineral and also fixation.

Explanation

A collection of different tissues worked together to perform a specific function or functions is
called an organ. Human body has different organs like stomach, eye, heart, lungs etc., are made up
of different type of tissues. Plants have organs such as leaves, stems, and roots.

Explanation

Tissue is a group of cells, organized for a specific function. Tissues have following features like
same shaped cells or different shaped cells to perform a common function. Human and other
animals are made up of nervous, epithelial, connective and muscle tissues. Plants have transport,
protective and ground tissues.

Explanation

Our body is made up of many different kinds of cells. Each type of cell is specialized to perform a
specific function. Depending on the function, cell has specific shape, size and may have some
components which other type of cells do not have.

Explanation

Inside a cell, there are many tiny structures called cell organelles. These organelles are responsible
for providing needs of the cell. They work to bring in food supplies, get rid of waste, protection and repair of the cell, and help it to grow and reproduce. Each one has a specific function to do for the
cell.

Explanation

As we have mentioned before, all cells have some common structure.
These are 1. Cell membrane 2. Cytoplasm, and 3. Nucleus (In most eukaryotic cells)
Nucleus not found in prokaryotes.

Explanation

The boundary of an animal cell is the plasma membrane, which is also called as cell membrane.
All animal and plant cells are enclosed or surrounded by a cell membrane.

Explanation

All animal and plant cells are enclosed or surrounded by a cell membrane as you learned before.
However, as you might have noticed previously that, animal cells often have an irregular shape,
whereas plant cells have a much more regular and rigid shape.

Explanation

Plant cells have an additional layer on the outer side of the cell membrane. This is called as the cell
wall, that provides a frame work for support and stability

Explanation

The cell wall is formed from various compounds, the main one being cellulose. Cellulose helps to
maintain the shape of the plant cell. This allows the plant to remain rigid and upright even if it
grows to great heights. Each cell is interconnected with its neighbouring cells through openings
called Plasmodesmata.

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Stem cells are quite amazing as they can divide and multiply while at the same time with their
ability to develop into any other type of cell. Embryonic stem cells are very special as they can
become absolutely any type of cell in the body, for example, blood cell, nerve cell, muscle cell or
gland cell. So, they are utilized by the Scientist and Medicos, to cure and prevent some diseases
like Spinal cord injury

Explanation

The cytoplasm includes all living parts of the cell with in the cell membrane, excluding the nucleus.
The cytoplasm is made up of the cytosol and cell organelles. The cytosol is a watery, jellylike
medium made up of 70% – 90% water and usually colourless.

Explanation

Cell organelles and structures present in a cell are endoplasmic reticulum, vacuole, ribosome, golgi
body, lysosome, mitochondria, centriole, chloroplast, surrounded by plasma membrane and cell
wall.

Explanation

In particular, the material inside and outside the nuclear membrane is known as Protoplasm. The
fluid inside the nucleus is known as the nuclear fluid or nucleoplasm and outside the nucleus is
called as cytoplasm.

Explanation

Mitochondria is an oval or rod-shaped double membrane bounded organelle. Aerobic respiratory
reactions take place with-in the mitochondrion to release energy. So, it is known as “the Power
House” of the cell. The energy produced within the mitochondrion is used for all the metabolic
activities of the cell.

Explanation

Chloroplasts are the only cell organelles that can produce food from the sun energy. Only plants
with chloroplast are able to do photosynthesis because they contain the very important green
pigment, chlorophyll. Chlorophyll can absorb radiant energy from the Sun and convert it to the
chemical energy which can be used by the plants and animals. Animal cells lack chloroplasts and
are unable to do photosynthesis.

Explanation

Various range of these plastids impart different colours to various parts of plant. Chromoplast
impart colour to flower and fruits. As fruits ripen, chloroplasts change to chromoplasts. Starch is
converted to sugar.

Explanation

Membrane bounded sacs are stacked on top of the other with associated secretory vesicles are
collectively known as Golgi complex.Functions of Golgi complex are the production of secretory substances, packaging and secretion. This is the secret behind the change in the colour and taste
of fruits.

Explanation

Lysosome- “Suicidal Bag”

Everything I touch, I destroy You will find organelles called as lysosomes, which are very small to
view using a light microscope. They are the main digestive compartments of the cell. They lyse a
cell, hence they are called “suicidal bag”

Explanation

Centrioles are generally found close to the nucleus and are made up of tube-like structures.
Centrioles or centrosomes are present only in animal cells and absent in plant cells. It helps in the
separation of chromosomes during cell division.

Explanation

Rough endoplasmic reticulum is rough due to the ribosomes attached to the membrane. which
helps in the synthesis of protein

Smooth endoplasmic reticulum. It is a network of tubular sacs without ribosomes on the
membrane. They play a role in the synthesis of lipids, steroids and also transport them within the
cell.

Explanation

Plant and animal cells have a nucleus inside the cytoplasm. It is surrounded by a nuclear envelope.
One or two nucleolus and the chromatin body are present inside the nucleus. During cell division,
the chromatin body is organised into a chromosome. Storage of genetic material and transfers
heredity characters from generation to generation are the functions of chromosome.