Cell Biology

Sieve tube cells do not contain any nucleus. Thus, they are called dead cells.

Ostrich egg is the largest cell. However, nerve cell is the longest human cell.

The size of a cell depends upon its oxygen requirement, its minerals and materials requirement and the regulation ability of its nucleus.

White blood cells protect the body against infection, and they can change their shapes continuously.

Cytoplasm is slightly acidic so as to protect the cell from pathogens.

Cells of kidney are the smallest cells of human body.

The smaller the cell, the more it will be active metabolically. For e.g., RBCs which are smaller as compared to other body cells carry the maximum oxygen to body parts.

In an animal cell, outer thin and rigid cell wall, chlorophyll containing plastids and glyoxysomes are absent.

Totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism, and it is demonstrated by all nucleated eukaryotic cells.

The lipoprotein, single unit membrane of ER is thinner than cell membrane so as to transport proteins and lipids to body parts.

Water is most abundant and important constituent of protoplasm. All the metabolic reactions of a body take place in water medium.

The study of cellular structures and components is called cytology. It was coined by Hertwig.

Robert Hooke is known as the 'father of cytology' as he had discovered the cell in an onion peel.

Golgi bodies are located near the nucleus and contain a stack of flattened cisternae structures. They help in the packaging and transport of lipids and proteins.

Proteins are synthesised by ribosomes present on the surface of RER.

The main function of SER is to synthesise lipids.

Mitochondrion takes energy from carbohydrates/food and forms ATP molecules, and is the power house of the cell.

Nucleus is the largest cell organelle, which can be easily identified under the microscope.

Bacterial nucleus is termed as 'nucleoid' as its nucleus does not contain a well defined nuclear membrane.

Transfer of chemical energy into utilisable biological energy takes place in mitochondia in the form of ATP.

Lysosomes are called 'suicidal bags' because of hydrolytic enzymes, which digest their own cell organelles.

Micochondria are called the 'power houses of the cell' because they contain ATP.

Violet and blue coloured waves are absorbed by chloroplasts, and green colour is reflected.

A green coloured pigment called chlorophyll is located in the chloroplast, which helps in the process of photosynthesis.

Dictyosomes secrete various essential vitamins and enzymes.

Smooth endoplasmic reticulum (SER) is the site of lipid synthesis.

Mitochondria is called the 'power house of the cell' as it stores energy in the form of ATP.

The cells, which are metabolically more active possess higher number of mitochondria because of higher energy requirement.

Infoldings of a mitochondria on which ATP synthesis occur are called the cisterns.

Due to the presence of ribosomes on the surface of endoplasmic reticulum, it appears rough.