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(c) nodal surface.

(b) (i) and (ii)

\(\bullet\)  The. region where there is probability density function reduces to zero is called nodal surface or a radial node. 

 \(\bullet\)  For ns orbital, (n-1) nodes are found in it.

(b) 17

n + 1 = 8

Electronic configuration of atom with atomic number 105 is [Rn] 5f¹⁴ 6d³ 7s²

(b) (ii), (iv) and (v)

(ii) l can have the values from 0 to n – 1 n = 2; possible l values are 0, 1 hence l = 2 is not possible. 

(iv) for l = 0; m = -1 not possible 

(v) for n = 3 l = 4 and m = 3 not possible.

The Clean Brigade members made rounds of the Fair spreading the message of cleanliness and they had vowed to keep the school premises spick and span during the Fair.

(b) hydrophytes

Smooth muscles occur in uterus.

Phloem like xylem is a complex tissue and consists of the following elements.

1. Sieve elements 

2. Companion cells. 

3. Phloem fibres 

4. Phloem parenchyma

If platelets are absent, this important defense reaction cannot occur, and protracted bleeding from small wounds (prolonged bleeding time) results.

Fishes: The heart of fishes has two chambers, an auricle and a ventricle. The deoxygenated blood enters the auricle and is transported to ventricle from where it reaches the gills for the process of oxygenation. From here the blood is circulated in the body. This is an example of single circulation where the blood crosses the heart only once.

Frogs: Amphibians have a three chambered heart, two auricles and one ventricle. This means that the oxygenated and deoxygenated blood gets mixed up and causes an insufficient supply of oxygen to body cells.

An organism can be composed of a single cell or many cells. An organism with a single cell is called unicellular organism. On the other hand, an organism with more than one cell is called multicellular organism.

Ancient Greek thinker Aristotle classified living beings on the basis of their habitat. He classified them into two groups, i.e. those living in water and those living on land. But his classification was too simple to justify inclusion of a particular organism into a particular group. 

Some examples of scientific bases of classification are as follows: 

Organization of nucleus: Nucleus may or may not be organized in an organism. On this basis, organisms can be divided into two groups, viz. prokaryotes and eukaryotes. 

(a) Prokaryotes: When nucleus is not organized, i.e. nuclear materials are not membrane bound; the organism is called prokaryote. 

(b) Eukaryotes: When nucleus is organized, i.e. nuclear materials are membrane bound; the organism is called eukaryote.

Aristotle classified organisms into two groups- plants and animals. The animals were further classified based on their habitat, i.e. whether they lived on land, in water, or in air. The plants were categorised as small medium and large.

On the basis of the complexity of cell structure, organisms are classified into eukaryotic and prokaryotic organisms. Further eukaryotic organisms are divided into unicellular and multicellular based on the number of cells present in the organisms.

The basis of classification is: 

● Type of cell (Eukaryotic or prokaryotic) 

● Number of cells present (unicellular or multicellular)

● Mode of nutrition (Autotrophic or heterotrophic)

It is necessary to classify organisms because it helps in the identification of living organisms as well as in understanding the diversity of living organisms.

Plants and animals are put into different categories on the basis of the Mode of nutrition. Plants are autotrophs, while animals are heterotrophs. Cell wall is present in plant cells, while it is absent in animal cells. Also, locomotion, absence of chloroplasts, etc. make them different. Plants do not need to move from one place to another, while most of the animals need to move in search of food.

We have to classify organisms because in our surrounding millions of organisms are there. Each organism is different from all others to a lesser or greater extent.

Disadvantages of two-kingdom classification are: 

• This system did not distinguish between the eukaryotes and prokaryotes, unicellular and multicellular organisms and photosynthetic (green algae) and non-photosynthetic (fungi) organisms. 

• There are some organisms which neither fall into plant nor animal kingdom like Lichens.

A lichen is not a single organism but a symbiosis among different organisms like fungus and a cyanobacterium or algae. Cyanobacteria are also referred to as blue-green algae despite the fact of being distinct from algae. The non-fungal part is known as photobiont that contains chlorophyll.

• They are unicellular and eukaryotic. 

• They use appendages such as hair-like cilia or whip-like flagella for moving around.

It includes algae, diatoms and protozoans. These are unicellular and the simplest form of eukaryotes exhibiting both autotrophic and heterotrophic mode of nutrition. Locomotion and movement are possible by whip-like flagella and hair-like cilia or finger-like pseudopodia. Examples are unicellular algae, diatoms and protozoans.

It includes all the plants that are non-motile, multicellular and eukaryotic organisms with their cell walls made up of cellulose. These are complex organisms which can perform photosynthesis. Plants comprise cells with thick cell walls.

Bacteria is one such organism which carries out all its body functions through a single cell. Belonging to kingdom Monera , the bacteria are single celled organisms which don’t have a well defined nucleus or organelles. But , they have special mechanisms to carry out metabolic functions through single cell only.

In situations where cells are grouped together to form an indivisible organism , the principle of division of labour is followed. All cells in these organisms are not identical and particular group of cells perform particular functions. This functional similarity of cells leads to their organisation in a specific manner which dictates their body design. This makes a basic distinction in the body design of organisms, simplifying the classification process.

These are multicellular, eukaryotic saprophytes. The cell wall of fungi is made up of chitin.

They feed on dead and decaying matter. They include mushrooms, rhizopus and mucor. Some fungi are symbiotic forming an association with algal cells. These symbionts are termed to be lichens.

There are many differences between plants and animals but they are placed in different categories on the basis of one important character:

• Mode of nutrition: Plants are autotrophic whereas animals are heterotrophic. 

The other differences are:

• Plant cells have a cell wall whereas animal cells don't. 
• Plant cells have a big central vacuole whereas animal cells have one or more smaller vacuoles.

The notochord is replaced by a spinal column during embryonic stage. Following are the main characteristics of vertebrates:

• Notochord present; which is replaced by spinal column.
• Dorsal nerve chord is present.
• Animals are triploblastic and coelomate.
• Animals have paired gill pouches.

Charles Darwin wrote “The Origin of Species” in 1859. It was his most famous work .

Plants prepare their own food by the process called photosynthesis. But animals are not preparing their own food on this bases are plants and animals put into different categories.

On this basis, organisms can be divided into two broad groups, i.e. autotrophs and heterotrophs. An autotroph makes its own food, while a heterotroph depends on other organisms for food.

Animals have jointed appendages which gives the name arthropoda. Exoskeleton is present which is made of chitin. This is the largest group of animals; in terms of number of species. Circulatory system is open, which means blood flows in the coelomic cavity. 

Examples: cockroach, housefly, spider, prawn, scorpion, etc.

Older organisms are called primitive and they have simple structure. Body structure of advanced organism is complex.

Advanced organisms as well as complex organisms both are of same type. Because they both do not have simple body structure.

Complexity in body design evolves because of necessity to adapt according to the changing environment. Hence, a complex organism would be an advanced one; in comparison to a simple organism.

The animal has soft body; which is enclosed in a hard shell. The shell is made of calcium carbonate. Circulatory system is open and kidney like organ is present for excretion. The body has well developed muscular feet for locomotion. 

Examples: Snail, mussels, octopus, etc.

The body is covered with spines, which gives the name Echinodermata. Body is radially symmetrical. The animals have well developed water canal system, which is used for locomotion. Skeleton is made of calcium carbonate. 

Examples: Starfish, sea urchins, etc.

Amoeba belongs to kingdom Protista.

The This kingdom comprises of Eukaryotic organisms that are mostly unicellular with some exceptional multicellular algae

i. temperature

ii. shape, volume, mass

iii. density

iv. neutral

The connecting link between annelida & arthropoda is Peripatus.

Largest invertebrate is giant squid.

1. Presence of special tube feet which help in locomotion & respiration. 

2. Presence of special “Water vascular system”. The water enters in it through a madriporite. 

3. Blood vascular, respiratory and excretory systems are absent. 

4. Less developed sense organs and nervous system.

i – d 

ii – e 

iii – a 

iv – b 

v – c.

Spices are the aromatic parts of tropical plant traditionally used to flavour food. Bark, roots, leaves, flowers or stems of certain plants primarily used for flavouring colouring or preserving food. 

(Eg.) roots – vetiver, 

leaves – curry leaves 

seeds – fenugreek 

flower bud – clove

The medicinal plants are Phyllanthus, Vallarai, Black nightshade, Tippili, Vetiver, Thuthuvalai, Neem and Tulsi.

i – c 

ii – a 

iii – b

iv – e 

v – d.

(d) Timber plants

Neem tree, Tulsi tree, Amla tree are the medicinal plants.

Bright colured flowers, smell and honey attract insects. As the insects go from one flower to another they leave the pollen grains from their body. This results in cross pollination.