The Invisible Living World: Beyond Our Naked Eye

A set of 30 fill-in-the-blank practice flashcards covering cell biology, microscopic discovery, levels of organization, microbial diversity, and practical biotechnology from Grade 8 Science Chapter 2.

Long ago, people discovered that a curved piece of glass shaped like a lentil seed could magnify objects, leading them to call it a __________.

lens

In Activity 2.1, a round-bottom glass flask filled with water placed over book letters acts like a __________ glass.

magnifying

In $1665$, Robert Hooke published the book titled __________ in which he first used the word "cell" after observing thin slices of cork.

Micrographia

The Dutch scientist known as the "Father of Microbiology" who first clearly described bacteria and blood cells in the $1660\text{s}$ was __________.

Antonie van Leeuwenhoek

When preparing an onion peel slide, the peel is immersed in a red-coloured stain called __________ for $30\text{ seconds}$ to colour the cells pinkish.

safranin

During microscope slide preparation of onion peel, a drop of __________ is added to prevent drying of the cells and improve visual clarity.

glycerin

To observe human cheek cells under a microscope, a drop of __________ is added to increase contrast and improve cell visibility.

methylene blue

The basic cellular structure that encloses the cytoplasm and nucleus and is porous to allow the entry of vital materials and exit of wastes is the __________.

cell membrane

A plant cell contains a large, empty-looking space called a __________ that stores substances, gets rid of wastes, and maintains cell shape.

vacuole

While a human nerve cell is elongated and branched, a human muscle cell is shaped like a __________.

spindle

The structural hierarchy in a complex organism proceeds as: Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ __________ $\rightarrow$ Organism.

Organ system

The inner cheek cells are thin and flat so that they can form a __________ lining on the inner surface of the cheek.

protective

The yellow yolk of an ostrich egg is the largest known single cell in the living world, measuring about __________ in diameter.

$$130\,\text{mm}\text{ to }170\,\text{mm}$$

A low-cost and foldable paper microscope designed by scientists to make the microscopic world accessible to many people is called a __________.

foldscope

Under pond water observation, the single-celled protozoan that is moving and characterised by an irregular shape is __________.

Amoeba

In soil suspension analysis, bread mould is classified as a fungus having a branched filament without chlorophyll and a __________ structure.

sac-like

Viruses differ from cellular microbes because they are microscopic and __________ entities that can only multiply when inside a living host cell.

acellular

Ancient Indian texts, including the Atharvaveda, use the word __________ to describe tiny visible ('Drishya') and invisible ('Adrishya') entities.

Krimi

Microorganisms do not infect pickles and murabbas because a high concentration of __________ acts as a preservative.

salt or sugar

In a compost container or pit, peels of fruits and vegetables are broken down into dark-coloured, nutrient-rich manure after __________.

$$2\text{--}3\,\text{weeks}$$

During the anaerobic breakdown of waste for biogas, bacteria release carbon dioxide and a high proportion of a combustible gas called __________.

methane

In $1971$, Dr. Ananda Mohan Chakrabarty developed a genetically engineered bacterium to break down __________, receiving a patent in $1980$.

oil spills

During bread and pastry preparation, yeast respires and produces bubbles of __________ gas, which causes dough to rise and become soft and fluffy.

carbon dioxide

During curd formation, the bacterium Lactobacillus feeds on the milk sugar known as __________ and ferments it into lactic acid.

lactose

Roots of legumes such as beans, peas, and lentils bear nodules harboring __________ bacteria, which trap nitrogen from the air.

Rhizobium

The microalga __________ is referred to as a superfood because it provides vitamin $B_{12}$ and contains more than $60\%$ of its body weight in protein.

Spirulina

In household or livelihood cultivation, Spirulina grown in a glass tank is ready to be harvested by filtering through a fine cloth after __________.

$$3\text{--}6\,\text{weeks}$$

Bacterial cells differ fundamentally from plant and animal cells because they lack a nuclear membrane and well-defined nucleus, having an undefined region termed a __________.

nucleoid

To observe subcellular structures in great detail, an electron microscope is used which can magnify a specimen about __________ times.

$$10,00,000$$

India has a long history of biogas utilisation, with one of its earliest biogas plants established in the late __________.

$$1850\text{s}$$