BIOLOGY 2 Marks Questions

Leaflets are present on a common axis (rachis) in case of pinnately compound leaves. In palmately compound leaves, the leaflets originate from the apex of the midrib.

	Fibrous root		Adventitious root
1.	In monocots, the primary root which develops from the rsdicle of the seed is short-lived and is replaced by a large number of roots arising from the base of the stem.	1.	These roots arise from any part of the plant other than the radicle of seeds.
2.	It is found in wheat and other cereals.	2.	It is found in babyan monstera, and other plants.

Actinomorphic: When flower can be divided into equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, Datura etc.

Various parts of plants are modified into underground structures to perform various functions such as stems, leaves, and even fruits. The stems in ginger and banana are underground and swollen due to storage of food. They are called rhizomes. Similarly, corm is an underground stem in Colocasia and Zamin-khand. The tips of the underground stem in potato become swollen due to the accumulation of food and forms tuber. Tubers bear eyes, which are subtended by a leaf scar. Basal leaves in onions become fleshy because of the accumulation of food. In peanuts, the flower after fertilization gets pushed inside the soil by growing a flower stalk. The formation of fruits and seeds takes place inside the soil.

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. It is of three types: alternate, opposite and whorled.

1. Alternate Arrangement of Leaves: In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in China rose, mustard and sun flower plants.
2. Opposite Arrangement of Leaves: In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants.
3. Whorled Arrangement of Leaves: If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia.

	Apocarpous		Syncarpous ovary
1.	The flowers with apocarpus ovary have more than one carpel. These carpels are free.	1.	The flowers with syncaprpous ovary have more than one carpel. However, these carpels are fused.
2.	It is found in lotus and rose flowers.	2.	It is found in the flowers of tomato and mustard.

	Racemose		Inflorescence
1.	Younger flowers are persent at the tip while older flowers are arranged at the base of this inflorescence. Such an arrangement is called acropetal succession.	1.	Younger flowers are persent at the tip while older flowers are arranged at the base of the inflorescence, while older flowers are present at the top. Such an arrangement is called basipetal succession.
2.	The main axis in racemose inflorescence continues to grow and produce flowers laterally.	2.	The main axis in cymose inflorescence has limited growth, which later terminates into a flower.

Placentation: The arrangement of ovules within the ovary is known as placentation. The placentations are of different types namely, marginal, axile, parietal, basal, and free central.

Superior ovary: In hypogynous flower, the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, brinjal.

Aestivation: The mode of arrangement of accessory floral organs (sepals and petals) in relation to one another in floral bud is known as aestivation. The main types of aestivation are valvate, twisted, imbricate, and vexillary.

Zygomorphic: When a flower can be divided into two similar halves only in one particular vertical plane, it is said to be zygomorphic, e.g., pea, gulmohar, bean, cassia.

During the flowering season, the apical meristem gives rise to the floral meristem. The axis of the stem gets condensed, while the internodes lie near each other. Instead of leaves, various floral appendages arise from the node. Therefore, it can be said that the flower is a modified shoot.

Differences between meristematic tissues and permanent tissues:

S.No.	Meristematic Tissues	Permanent Tissues
i.	Cells keep on dividing.	Cells stop dividing.
ii.	Growth is the basic function.	Protection is the basic function.
iii.	Found in tips of roots and stem.	Found in girth and periphery.

Reasons for seed dormancy:

1. Hard seed coat.
2. Impermeable layers prevent uptake of water.
3. ABA inhibits growth and delays germination.
4. Some seeds have immature embryo which delays germination.

Methods to break seed dormancy:

1. Physical dormancy is broken by changes in temperature and other environmental conditions.
2. Physical dormancy is also broken when the seed passes through the gut of an animal.
3. Mechanical dormancy is broken by help from some external agents. For example; an animal may break the hard seed coat.
4. Chemical dormancy is broken by enzymatic actions.

In a maize grain, the seed coat is membranous and is fused with the fruit wall. In fact, a maize grain is a ripened ovary which contains a ripened ovule. Hence, a maize grain is usually called a fruit and not a seed.

1.  

• It stores food materials.
• It acts as an organ of perennation to tide over unfavourable conditions and helps in vegetative reproduction.

2.  

• Axillary bud of watermelon is modified into tendril, which helps the plant to climb on the support.

• Bract is a small reduced leaf-like structure, found at the base of the pedicel of the flower.
• If a flower has a bract, it is called bracteate.
• If a flower does not have a bract, it is called ebracteate.

Plants found in the marshlands have root modifications called Pneumatophores which are negatively geotropic that is they come out of the ground and grow vertically upwards to take up oxygen from the atmosphere.

1. Belladonna, Ashwagandha.
2. Tobacco.
3. Chilli.
4. Potato, tomato, brinjal.

1. Underground parts of a plant are not always roots. Sometimes stem or stem branches occur underground to perform some special functions. For example, potato tuber is a modified stem which is underground. A potato tuber shows nodes and internodes, scale leaves and buds at the nodes. It also has an apical bud at the tip of potato tuber which confirms it as a stem.
2. Flower is a modified shoot consisting of a highly reduced stem branch to form thalamus in which the nodes are borne only towards the tip. The floral parts, i.e., sepals, petals, stamens and carpels are arranged in their respective whorls and arise from nodes. The growing point of floral bud is used up in the production of floral organs.

Differences between xylem and phloem:

S.No.	Xylem	Phloem
i.	Composed of tracheids, vessels and xylem parenchyma.	Composed of sieve tubes, companion cells and phloem parenchyma.
ii.	Facilitate conduction of water and minerals from roots.	2. Facilitate conduction of food from leaves.

1. Flower is the reproductive unit of plant. It is considered, as a shoot because the position of the buds of both flower and shoot is same and can be terminal or axillary in position.
2. Floral whorls are arranged on the thalamus, swollen end of axis.

Sunflower is not a single flower rather it represents a complete inflorescence, called capitulum or racemose head. Small sessile flowers called florets develop compactly over discoid peduncle. They open in centripetal order. They are surrounded and protected by an involucre of bracts. The florets are of two types namely, ray florets and disc florets. Ray florets are usually female and zygomorphic and disc florets are bisexual and actionomorphic. In Helianthus, the ray florets are towards the periphery and disc florets are at the centre of the inflorescence.

Solitary, axillary or terminal, umbellate or occasionally helicoid and scorpoid cyme.

1. Dalbergia sisso.
2. Indigofera tinctoria.
3. Vicia faba (broad bean).
4. Medicago sativa (alfalfa).

S. No	Solanaceae	Fabaceae
(i)	Ovary is bicarpellary, syncarpous.	Ovary is monocarpellary.
(ii)	Ovules are present on swollen axile placenta.	Ovules are present on marginal placenta.
(ii)	Ovary is bilocular.	Ovary is unilocular.

Differences between pollen and pollinium are as follows:

	Pollen	Pollinium
i.	Pollen or Pollen grain is single microspore and represents male gametophyte.	Polliniumk represents group of pollen grains held together.
ii.	Pollen grains are found in number of angisopermic families viz. Liliaceae, Convulvulaceae, Malvaceae, etc.	Pollinium is found in Orchidaceae and Asclepiadaceae.

1. Calyx-Sepals.
2. Corolla-Petals.
3. Androecium-Stamens.
4. Gynoecium-Carpels.

• Cells are small.
• They are thin-walled.
• They have dense protoplasm.
• They divide repeatedly.

• Structure of Parenchyma: It is composed of round, spherical or polygonal cells. Cells are isodiametric with thin walls. The tissue has intracellular spaces.
• Function: Photosynthesis, food storage and secretion.

Differences between free central and axile placentation are as follows:

1. In axile placentation, ovary is partitioned into chambers whereas in free central placentation ovary is single chambered.
2. The ovule bearing column occurs in the central region where septa meet in axile placentation whereas in free central placentation ovule bearing column lies free in the centre of ovary and septa are absent.

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Reticulate venation is a characteristic of dicots but there are exceptions and they are also found in some monocots like Alocasia, Smilax etc, while parallel venation is a characteristic if monocots but they are alsofound in dicots like corymbium, calophyllum etc as exceptions.

1. Lamina.
2. Pneumatophores.
3. Gamosepalous.
4. Adventitious roots.

1.  

S. No	Reticulate Venation	Parallel Venation
(i)	When the midrib and its branches make a network (reticulum) on the lamina, it is called reticulate venation.	When the veins on the lamina run parallel to one another, it is called parallel venation.
(ii)	It is characteristically found in dicot plants.	It is characteristically found in monocot plants.

2.  

• Thorn is a stem modified into a woody, straight and pointed structure.
• Spine is a leaf modification in arid plants to reduce water loss and protection of plants from browsing animals.

Difference between androecium of Solanaceae and Liliaceae are:

S.No.	Solanaceae	Liliaceae
i.	Five stamens, epipetalous, filaments of unequal length, Anther dithecous, connivent (in contact with each other), introse.	Stamen 6, arranged in two whorls of three each, epipetalous, anthers dithecous, dorsifixed or versatile, introse.

Differences between stamen and stami-node are as follows:

	Stamen	Stami-node
i.	It is fully developed male reproductive part of a flower.	It is under developed male reproductive part of a flower.
ii.	Its anther contains functional pollen grains.	Fuctional pollen grains are absent.

Rhizome is a type of underground stem, these are modified plant structures derived from stem tissues but they exists under the soil surface. In Plants, seedlings shows two axes of growth, structures that developed downward called as roots and those developed upward out of the soil called stems. In ginger plant development is upward out of the soil and hence, the stems are modified to store energy, these stems have nodes with buds where leaves and flowers arise at specific location. Rhizome usually produces aerial stem and underground roots from these buds. So, it looks like and acts like a root but is different because it grows horizontally.

Differences between pedicel and peduncle are as follows:

	Pedicel	Peduncle
i.	It is stalk of the flower.	It is flower bearing axis of the inflorescence.
ii.	A pedicel bears a single flower.	A peduncle generally bears several flowers.

The root that arise from parts of plant other than radicle are called adventitious roots. Pneumatophores-for respiration, Stilt roots-for support, Prop roots-for support.

S. No	Fabaceae	Solanaceae
(i)	There are ten stamens.	There are generally five stamens.
(ii)	Stamens are free from the corolla.	Stamens are attached to petals-epipetalous.
(iii)	Nine stamens are united by their filaments and one is free-diadelphous.	Stamens are free from one another.

Some plants of arid regions modify their stems into flattened {Opuntia), or fleshy cylindrical {Euphorbia) structures. These modified stems of indefinite growth are called phylloclades. They contain chlorophyll and carry out photosynthesis.

• Structure of Collenchyma: The cells are round, spherical or polygonal. Intracellular space is present in the tissue. Cells are thickened at corners due to cellulose, hemicellulose or pectin dposition. They are found in young stem and petiole of leaf.
• Function: Provide mechanical support to growing parts of a plant.

1. Passiflora- Axillary.
2. Luffa- Extra-axillary.
3. Vitis- Apical.
4. Antigonon- Floral.

Differences between bract and bracteole are:

S.No.	Bract	Bracteole
i.	It is a small leaf-like structure borne on the mother axis from where a flower develops.	it is a small leaf-like structure present on the pedicel of a flower.
ii.	It bears a flower in its axil.	It is borne over the stalk of the flower.
iii.	A single bract occurs at one place.	Generally two bracteoles occur over the pedicel of a flower.

S. No	Dicot Seed (Gram)	Maize Grain
(i)	The seed coat is distinct from the pericarp.	The seed coat and the pericarp are completely fused.
(ii)	There are two cotyle dons, attached laterally on the embryonal axis.	There is a single coty ledon, called scutellum, pushed towards one side.
(iii)	There is no protective covering for the plumule and radicle.	Plumule is covered by coleoptile and radicle by coleorhizae.
(iv)	Food is stored in cotyledons.	Food is stored in the endosperm.

e.g., Neem, Rose. e.g., Silk cotton.

3. One should get rid of home-sickness and leave his home-town to grab most of the opportunities available.

If someone becomes home-sick and remains confined at the place he is familiar with, his vision does not become wide. The person lives like as if living inside a cocoon; isolated from the outer world. When we see new places, we get the opportunity to learn many new things. We learn how to make friends with strangers in a strange place. Learning to live in unfamiliar environment also gives some survival benefits as it makes the person more adaptive to the changed situation.

No	Hypogeal germination	No	Epigeal germination
(i)	Rapid growth and elongation of epicotyl.	(i)	Rapid growth and elongation of hypocotyl.
(ii)	Cotyledons remain non-green and non- photosynthetic.	(ii)	Cotyledons become green and photosynthetic.
(iii)	Examples: Castor, bean	(iii)	Examples: Maize, rice

Role of cotyledons and endosperm: Cotyledons and endosperm act as food reservoir. food in them becomes available to the embryo during germination. Once the first set of leaves emerge, the sapling begins photosynthesis. Till then, food is supplied by endosperm and cotyledons.

Differences between reticulate and parallel venation are:

S.No.	Reticulate Venation	Parallel Venation
i.	Veins are not oriented parallel to one another.	Veins are oriented parallel to one another.
ii.	Smaller veins produce a network or reticulum.	A reticulum is not produced.
iii.	It is the characteristic feature of dicotyledons.	it is the characteristic feature of monocotyledons.

1. Stamens of brinjal are epipetalous, as the stamens are attached to the petals.
2. Stamens of lily are epiphyllous, as the stamens are attached to the tepals, that make up the perianth.

• Trimerous flowers are those where the floral appendages are in threes or multiples of three.
• Monocotyledonous plants like lily, orchids, etc. generally have trimerous flowers.

Cambium is present between xylem and phloem, in open vascular bundle. They have the capability to undergo secondary growth. They are found in dicot stems. Cambium is absent in closed vascular bundle. They don't have the capability to undergo secondary growth. They are found in monocot stems.

1. Solanum nigrum.
2. Pisum sativum.

1. The use of network of veins on lamina is to conduct water, mineral salts and food as they contain vascular tissues.
2. Venation is of two types, reticulate venation and parallel venation.

Differences between spike and spadix are as follows:

	Spike	Spadix
i.	A spathe-like covering is absent.	The inflorescence is covered by a large bract called spathe.
ii.	The peduncle is nonfleshy.	The peduncle is fleshy.
iii.	The whole penducle is covered by flowers.	The apical part of peduncle, called appendix, is naked, i.e., without flowers.

1. Cucumber-Stem tendril.
2. Pea-Leaf or leaflet tendril.
3. Pumpkin-Stem tendrilla.
4. Grapevine-Stem tendrils.

Simple tissues are composed of similar cells. Complex tissues are composed of dissimilar cells. Simple tissues provide bulk and mechanical support to plants. Complex tissues are meant for transportation of substances and they also provide mechanical support.