Studying homology and analogy with the help of models/charts of animals and models/charts/specimens of plants

---

Aim

To study homology and analogy with the help of models/charts of animals and models specimens of plants.

Material Required

Plant specimens such as Bougainvillea, cucurbits, potato and sweet potato. Animal models like bird, butterfly, forelimb of frog.

Theory

Homologous organs: The organs which perform different functions in different species but have similar basic structure and similar embryonic origin are called homologous organs.

Analogous organs: The organs which are quiet different in fundamental structure and embryonic origin but perform same function and may superficially look alike in entirely different species are called analogous organs.

Procedure

• Take the specimens/models/charts and observe them carefully.
• Record the structure and function of each specimen.
• Draw their neat and labelled diagrams.

Observations

A. Tendrils of cucurbits and spines of Bougainvillea

• Tendrils of cucurbits are modified stem which are used to climb a support.
• Spines of Bougainvillea are modified stem which are meant for protection.
• Both tendril of cucurbits and spines of Bougainvillea have same basic structural design but perform different functions. So, they are homologous organs.

B. Forelimb of frog and forelimb of bird

• The forelimb of frog consists of upper arm, fore arm, wrist, palm and five fingers. The upper arm is having humerus, fore arm with radius and ulna, wrist with carpels, palm have metacarpels and fingers have phalanges. The forelimb of frog helps the animal to prop up the front end of the body at rest and acts as a shock absorber when the animal lands on the ground after a leap.
• The forelimb of birds also has same basic plan of structure with an upper arm having humerus, a fore arm with radius and ulna, a wrist with carpels, a palm with metacarpels and five fingers with phalanges. The forelimb of the bird helps in flying.
• Both forelimbs of frog and bird show sinilarity in basic structure but perform entirely different function. So, they are homologous organs.

C. Potato and sweet potato

• In potato, eyes are present which are actually nodes.
• Potato is a modified stem which is adapted to store the food.
• Sweet potato is a modified root which is meant for storage of food.
• Both potato and sweet potato are structurally different but they perform the same function, i.e., storage food. So, they are analogous organs.

D. Wings of butterfly and wings of bird

• The wings of butterfly are extensions of integuments which are supported by a few muscles and used for flying in the air.
• The wings of birds are formed of limb bones covered with flesh, skin and feathers. Birds also use their wings for flying.
• Both wings of butterfly and wings of birds are structurally different but they perform the same function. So, they are anologous organs.

Result And Discussion

• Homologous organs have same structure but are functionally different.
• Analogous organs have same function but are structurally different.

Precautions

• The specimens should be fresh and clean.

---

Class 10 Physics Practicals

• To study the dependence of current on the potential difference with graph
• Determination of equivalent resistance of two resistors when connected in series
• Determination of equivalent resistance of two resistors when connected in parallel
• Determination of the focal length of Concave mirror by obtaining the image of a distant object
• Determination of the focal length of Convex lens by obtaining the image of a distant object
• Tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence
• Tracing the path of the rays of light through a glass prism

Class 10 Chemistry Practicals

• Finding the pH of the samples by using pH paper/universal indicator
• Studying the properties of acids and bases (HCl & NaOH) on the basis of their reaction
• Performing and observing the reactions and classifying them into: i. Combination reaction, ii. Decomposition reaction, iii. Displacement reaction and iv. Double displacement reaction
• Observing the action of Zn, Fe, Cu and Al metals on the salt solutions
• Studying the properties of acetic acid (ethanoic acid)
• Studying saponification reaction for preparation of soap
• Studying the comparative cleaning capacity of a sample of soap in soft and hard water

Class 10 Biology Practicals

• Preparing a temporary mount of a leaf peel to show stomata
• Showing experimentally that light is necessary for photosynthesis
• Experimentally show that carbon dioxide is given out during respiration
• Studying (a) binary fission in Amoeba, and (b) budding in yeast with the help of prepared slides
• Studying homology and analogy with the help of models/charts of animals and models/charts/specimens of plants
• Identification of the different parts of an embryo of a dicot seed (Pea, gram or red kidney bean)