Test: Roots, Stems and Leaves - 3 - ACT MCQ

Stilt roots occur in sugarcane. These are adventitious support roots that are common among mangroves.
They grow down from lateral branches, branching in the soil. Stilt roots arise from the first few nodes of the stem.

Stilt roots in Sugar cane:

The lateral branches in the Banyan Tree grow vertically downward into the soil and act as pillars. Prop or pillar or columnar roots are pillar-like roots that give extra mechanical support to heavy stem branches.

Growth of taproots is towards gravity.
Typically, a taproot is very thick. It is tapering in shape and grows directly downward into the soil towards the force of gravity.

In wheat plant, the roots originate from the base of the stem and constitute the fibrous root system.

The inflorescence is a collection of flowers in a particular branching pattern that does not contain full-size leaves among the flowers.

An actinomorphic flower is a type of flower that possesses radial symmetry. An actinomorphic flower can be divided into three or more identical parts, each of which are identical to each other when based on the rotating point of the centre of the flower.

In Solanaceae, flowers have 5 petals with valvate aestivation and 5 stamens. The filament of stamens are connected with the petals. It is known as an epipetalous condition.

Functions of Stem:

• It supports and holds leaves, flowers, and fruits.
• The stem allows the leaves to arrange in a way that they are able to receive direct sunlight in order to efficiently perform photosynthesis. The arrangement and position of leaves also allow for gas exchange.
• The xylem and phloem present in the vascular bundles of stems conduct water and minerals across the plant.
• Stems bear flowers and fruits in a position that facilitates the processes of pollination, fertilization, and dispersion of seeds.
• Some stems undergo modification to store food and water.
  Example: Succulents
• Few green stems contain chloroplasts and are capable of carrying out photosynthesis as well.
• Some stems are modified to carry out vegetative propagation which is a form of asexual reproduction seen in plants.

Thorns are hard, pointed straight structures for protection. In Bougainvillea, thorns are modifications of stem. These are used for protection against grazing animals.

Plant make their own food in the presence of light as well as the exchange of gases also takes place.

Option A: The arrangement of veins on the leaves is known as venation.

Option B: Vernation is the phenomenon of the arrangement of leaves in the bud.

Option C: The arrangement of the flowers on a plant is known as Inflorescence.

Option D: The arrangement of leaves on the stem branches is known as phyllotaxy. Alternate, opposite, whorled, and basal are different arrangements of leaves on the stem.

Hence, option D is correct.

• Victoria is a genus of water-lilies, in the plant family Nymphaeaceae, with very large green leaves that lie flat on the water's surface.
• Victoria amazonica has a leaf that is up to 3 metres (9.8 ft) in diameter, on a stalk up to 8 metres (26 ft) in length. The genus name was given in honour of Queen Victoria of the United Kingdom.

This is the correct option as this statement is false. Veins provide rigidity to the leaf blade and act as channels for transporting water, minerals and food materials.

• Root system helps in absorption of water and minerals from soil.
• In plants like mangroves, breathing roots called pneumatophores are present.
• Pneumatophores grow vertically upwards and exchange gases through lenticels.
• Plants that grow tall derive their additional mechanical support by sending pillar like woody roots called prop roots.

• Weak stems are aerial stems that are further classified into trailer, creeper and climber.
• Stems in rhizome, tuber and bulb grow under the ground.
• In some plants, stems are modified into thorns for defense.
• Stems in corn grow under the ground.

• In bulb, stem is underground and condensed with fleshy leaves.
• Leaves are arranged in concentric fashion.
• In onion, a single bulb is present whereas in garlic many bulbs combine to form a bigger bulb.
• Scale leaves are present on the bulb.

• Lamina contains veins and veinlets that transmit water to different regions of the leaf.
• Petiole is flexible thin structure that helps in fluttering of leaves in the air.
• Based on the presence or absence of petiole, plants are classified into petiolate and sessile respectively.
• Since petiole is absent in grass, it is considered to be sessile.
• Legumes have a swollen leaf base called Pulvinus.

In roots, the root hairs arise from zone of maturation. This zone is a differentiated zone. The function of root hairs is to collect water and mineral nutrients present in the soil and take this solution up through the roots to the rest of the plant. As root hair cells do not carry out photosynthesis, they do not contain chloroplasts.

In a flower, the arrangement of sepals and petals with respect to each other is called aestivation.

This is the correct option. Sepals are the first to form from the receptacle. They are usually green in colour and leaf-like in structure.

The stamens in a flower may either remain free (polyandrous) or may be united in varying degrees. Stamens may be united into 1 bunch or 1 bundle (monoadelphous) as in china rose or 2 bundles (diadelphous) as in pea or into more than 2 bundles (polyadelphous) as in citrus.

Stamens attached to petals are epipetalous. The stamens in a flower are collectively called the androecium.

The thalamus or the receptacle is the condensed structure on the pedicle from which the floral organs arise. The thalamus typically has the nodes and internodes but the internodes are highly condensed or reduced. 

(A) Mother axis is the branch that bears the inflorescence or the flower.

(B) Thalamus (also called torus) is the axis of the floral shoot which is the direct prolongation of the pedicel and bears four sets of floral members.

(C) Root is the vegetative structure that arises from the radicle.

(D) Pedicel is the stalk that has thalamus at the end. It bears the flowers. It is attached to the mother axis.

Hence, option B is correct.

The androecium is the third whorl of a flower whose individual unit is called the stamen. It is the male reproductive organ whorl.

(A) Anthers are the parts of the stamen in which pollen grains are formed.
(B) Stamens are the male reproductive structures, collectively called the androecium.
(C) Filaments are the parts of stamens that connect the anthers to the thalamus.
(D) Tepals are the units of the whorl called the perianth.

Hence the correct answer is 'Stamens'

► The condition of stamens in which the stamens are united in a single bundle or group is called monadelphous. It is seen in Hibiscus.

► Polyadelphous is the condition in which stamens are united to form more than two bundles. It is seen in Ricinus.

Syncarpous gynoecium has two or more fused carpels. Flowers that bear a gynoecium but no androecium are called carpellate.
If a gynoecium has multiple carpels fused into a single structure, it is syncarpous.

A typical flower that has an ovary placed superior with respect to the other floral organs is called hypogynous. The other floral organs are attached below the ovary to the receptacle.
Example: China rose, mustard, Datura.

The part of the ovary where the funiculus attaches is referred to as the placenta.

In flowering plants, placentation occurs where the ovules are attached inside the ovary. 

The pappus is the modified calyx, the part of an individual floret, that surrounds the base of the corolla tube in flower heads of the plant family Asteraceae.

• Arrangement of ovules in the ovary is placentation.
• In flowering plants, placentation occurs where the ovules are attached inside the ovary.
• The ovules inside a flower's ovary are attached via funiculi, the plant part equivalent to an umbilical cord. The part of the ovary where the funiculus attaches is referred to as the placenta.