CBSE Class 7 Science Advanced Biology Basis of Classification Short Answer Questions Set 01

Short Answer Questions

Question 1. Why is classification of living organisms important?
Answer:
There are millions of organisms on earth, and it is difficult to study each of them separately.
Grouping organisms by their similarities makes the study easier.
It also shows the similarities and differences between organisms and helps us find out whether two organisms have a similar origin.
In simple words: Sorting into groups turns a huge list into a manageable one.

Teacher's Note:
1. Give at least two advantages in the exam.
2. Think of a library where books are sorted by subject.

Question 2. Differentiate between family and order.
Answer:
A family is a group of related genera. For example, the genera of lion, tiger and cat form the family Felidae.
An order is a group of related families. For example, the family Felidae and the family of wolf belong to the order Carnivora.
Order is a higher level than family.
In simple words: Several families make one order.

Teacher's Note:
1. Draw a small ladder: genus, family, order.
2. A higher level contains more kinds of organisms.

Question 3. Give a note on Aristotle's system of classification.
Answer:
Aristotle divided all living organisms into two groups, plants and animals.
Plants were grouped by the stem: herbs (no woody stem), shrubs (small woody stem) and trees (big woody stem).
Animals were grouped by habitat: aerial (live in air), aquatic (live in water) and terrestrial (live on land).

In simple words: Plants sorted by stem, animals sorted by where they live.

Teacher's Note:
1. Draw the tree chart for full marks.
2. Aristotle was a Greek scientist.

Question 4. What were the main features selected for Whittaker's five-kingdom classification?
Answer:
Whittaker divided organisms into Monera, Protista, Fungi, Plantae and Animalia using three features.
1. Cellular organization: prokaryotic or eukaryotic.
2. Body organization: unicellular or multicellular.
3. Mode of nutrition: autotrophs or heterotrophs.
In simple words: Type of cell, number of cells and way of getting food.

Teacher's Note:
1. Learn the three features as a list.
2. Each feature separates some kingdoms from the others.

Teacher's Note:
1. A table is the best format for 'compare' questions.
2. Always add an example.

Question 6. Explain the main features of organisms coming under the kingdom fungi.
Answer:
Fungi are eukaryotic organisms. Some are unicellular (yeast) and some are multicellular (mushroom, bread mould).
They are heterotrophic because they cannot make their own food.
They are of two kinds: saprophytes, which feed on dead and decaying matter, and parasites, which get food from a host organism.
In simple words: Fungi are eukaryotic feeders on others, either dead or living.

Teacher's Note:
1. Yeast is a unicellular fungus.
2. Fungi do not have chlorophyll, so they cannot make food.

Teacher's Note:
1. Both kingdoms are multicellular and eukaryotic.
2. Mention at least four points.

Teacher's Note:
1. The only structural difference is the nucleus.
2. Monera cells have a nucleoid instead.

Question 9. What rules have to be followed while writing a scientific name?
Answer:
1. The genus name starts with a capital letter.
2. The species name starts with a small letter.
3. When handwritten, the genus and species names are underlined separately.
4. When typed, the name is written in italics.
Example: Homo sapiens.
In simple words: Capital for genus, small for species, underline or italicise.

Teacher's Note:
1. These four rules are the universal rules of nomenclature.
2. Always give an example.

Teacher's Note:
1. Ask: nucleus? cells? food? for each organism.
2. Catla is a fish, hence an animal.

Question 11. Suppose you accidentally find an old preserved permanent slide without a label. In your effort to identify it, you place the slide under a microscope and observe the following features: unicellular, no well-defined nucleus and multiple cilia. What would you identify it as? To which kingdom does it belong?
Answer:
The organism is unicellular and has no well-defined nucleus, so it is a prokaryote.
Such an organism is a bacterium, and bacteria belong to the kingdom Monera.
In simple words: No true nucleus plus a single cell means a bacterium, which is in Monera.

Teacher's Note:
1. The nucleus is the deciding feature here.
2. The hair-like projections are taken to be the surface appendages of the bacterial cell.

Question 12. Are humans closer to mouse or chicken? Explain.
Answer:
Humans are closer to the mouse.
Humans and mice are both mammals and belong to the class Mammalia, while chickens are birds and belong to the class Aves.
Sharing a lower group means they are more closely related.
In simple words: Sharing the same class makes humans and mice closer.

Teacher's Note:
1. Compare the lowest level they share.
2. Mammals share a class; birds are in a different class.

Question 13. If you are given the following set of animals, how would you find a common taxon to classify them? Dog, Wolf, Fox, Jackal.
Answer:
Compare their characters and find the lowest level of classification that includes all of them.
All four animals belong to the same family, Canidae (the dog family). Members of this family are called canids.
So the common taxon is the family Canidae.
In simple words: They all belong to the dog family.

Teacher's Note:
1. Move up the hierarchy until the group is shared by all.
2. Family is a level above genus.

Question 14. Banyan tree and algae both are grouped under kingdom plantae, yet there are remarkable differences in their appearance. What makes them to be grouped together?
Answer:
Both have chloroplasts and a cell wall.
Both can make their own food by photosynthesis, so both are autotrophs.
Because of these common characters they are placed in the same kingdom, Plantae.
In simple words: Different looks, but the same way of making food.

Teacher's Note:
1. Grouping depends on basic characters, not appearance.
2. Chloroplast and cell wall are the key common features.