Biology Test 278

Reticulate venation is a characteristic in Dicotyledonous leaves. In reticulate venation, veins are interconnected and form a web-like network. There is a prominent vein called the midrib from which many small veins arise which finally form a net-like structure in the lamina. The veins vary in thickness in the reticulate venation of the dicot leaves.

Vascular bundles in which cambium is present between xylem and phloem are called open vascular bundles and those in which cambium is absent are called closed vascular bundles.

Secondary growth occurs in most seed plants, but monocots usually lack secondary growth. If they do have secondary growth, it differs from the typical pattern of other seed plants. The formation of secondary vascular tissues from the cambium is a characteristic feature of dicotyledons and gymnosperms.

Exarch xylem is the arrangement in which the protoxylem (the first formed primary xylem cells in a plant shoot/root) is directed towards the periphery and metaxylem (later formed primary xylem cells in a plant shoot/root) is directed towards the centre. Its development follows a centripetal pattern and is characteristic of roots. 

Thus the correct answer is option D.

Zygomorphic : These are flowers that can only be divided into two equal halves by one particular vertical plane. An example is the flower of Cassia.

Hypogynous : In these types of flowers, the gynoecium occupies the highest position while the other parts are situated below it. The flower is said to have a superior ovary and is hypogynous. An example of a hypogynous flower is mustard.

Perigynous : In these flowers, the gynoecium is located in the center and other floral parts are located on the rim of the thalamus almost at the same level. The ovary here is said to be half inferior. Plum flowers are examples of perigynous flowers.

Epigynous : In these flowers, the margin of thalamus grows upward enclosing the ovary completely and gets fused with it, the ovary is said to be inferior as the other floral parts are situated above the ovary. An example of an epigynous flower is cucumber.

Earthworms respire only through the moist skin which is permeable to gases and Leeches also breathe through the skin.

Frogs don't respire always through the skin whereas Fishes respire through gills.

Hence, the correct option is C.

NCERT Reference: Topic- RESPIRATORY ORGANS” of chapter "Breathing and Exchange of Gases" of NCERT 

The volume of air remaining in the lungs even after a forcible expiration is called residual volume.

This residual volume prevents the lungs from collapsing.

Hence, the correct option is B.

NCERT Reference: Topic- Respiratory Volumes and Capacities” of chapter "Breathing and Exchange of Gases" of NCERT

The narrow tubes found inside the lungs are called bronchioles. 

When we breathe, air travels from the nose or mouth, and goes down the trachea and reaches the part called the carina.

From here the tube branches into two, creating two bronchi that lead to the left and right lung each.

From there onwards, the bronchi split into smaller and smaller bronchioles until it terminates in the alveoli where gas exchange occurs.

Hence, the correct option is C.

NCERT Reference: Topic- Human Respiratory System” of chapter "Breathing and Exchange of Gases" of NCERT.

The pleural membranes are two layers of the serous membrane which enclose and protect the lung.

The superficial layer is called the parietal pleura and lines the wall of the thoracic cavity.

The deep layer is called the visceral pleura and covers the lungs themselves.

Hence, the correct option is B.

NCERT Reference: Topic- Human Respiratory System of "Breathing and Exchange of Gases" of NCERT 

The trachea serves as a passage for air, moistens and warms it while it passes into the lungs, and protects the respiratory surface from an accumulation of foreign particles.

Hence, the correct option is C.

NCERT Reference: Topic-  Human Respiratory System” of chapter "Breathing and Exchange of Gases" of NCERT