Rajasthan Board RBSE Class 11 Biology Chapter 20 Inflorescence
RBSE Class 11 Biology Chapter 20 Multiple Choice Objective Questions
Question 1.
In Racemose inflorescence growth of floral axis is
(a) Limited
(b) Continous
(c) Unlimited
(d) Discontinuous
Question 2.
Compound recime is
(a) Mulberry
(b) Wheat
(c) Amaltas
(d) Rye
Question 3.
Name the inflorescence in which flowers are sessile and unisexual
(a) Catkin
(b) Spike
(c) Penicle
(d) Racemose raceme
Question 4.
Colecassia is example of:
(a) Spadix
(b) Spike
(c) Catkin
(d) Spikelet
Question 5.
Which of the following is an example of Corymb inflorescence?
(a) Coriander
(b) Fennel
(c) Fenugreek
(d) Iberis
Answers:
1. b, 2. c, 3. a, 4. a, 5. d
RBSE Class 11 Biology Chapter 20 Very Short Answer Questions
Question 1.
Name the plant which has Umbel inflorescence.
Answer:
Allium cepa (onion), Hydrocotyle asiatica.
Question 2.
How many types of florets are found in Capitullum type of inflorescence? Give examples of Capitullum type of inflorescence.
Answer:
Sunflower, marigold, (all members of Compositae).
Question 3.
Which two possibilities exist in solitary cymose type of inflorescence?
Answer:
When only flower is present on floral axis. On the basis of position of flower it may be of two type
- Solitary axillary: e.g., China rose
- Solitary terminal: e.g., Rose, Argemone
Question 4.
What are the differences between racemose and cymose type of inflorescence?
Answer:
| Racemose or indeterminate inflorescence | Cymose or determinate inflorescence |
| 1. Racemose type of inflorescence, the main axis continues to grow indefinitely and is not terminated into a flower (hence the name indeterminate). | 1. Cymose type of inflorescence, growth of the main axis is soon checked due to the development of a flower at its apex. Here, the main axis branches immediately below the terminal flower. |
| 2. It gives off flowers on lateral sides in acropetal succession, i.e., the lower or outer flowers are older. | 2.These lateral branches also terminate into a flower. |
| 3. Than the upper or inner flowers. | 3. Terminal flower being The oldest, the development is called basipetal and order of opening of flowers is called centrifugal. |
Question 5.
Differentiate Scorpioid with helicoids inflorescence.
Answer:
RBSE Class 11 Biology Chapter 20 Short Answer Questions
Question 1.
How many types are of Monochasial inflorescence? Give example of each.
Answer:
Uniparous or monochasial cyme: This is a cymose inflorescence where the main axis terminates into flower and produces only one lateral branch which also terminates into a flower. Depending upon the sequence of lateral branches uniparous cyme is of following two types
- Scorpioid cyme (cincinnus or rhipidium): A uniparous cyme in which the successive lateral branches develop on alternate sides in a zig-zag manner is called scorpioid cyme; e.g., Ranunculus bulbosus, Heliotropium, etc.
- Helicoid cyme (drepanium or bostryx): This is a uniparous cyme in which the lateral branches develop successively on the same side forming a sort of helix; e.g., Begonia. Juncus, etc.
Question 2.
What are the differences between Dichasial and Multichasial inflorescence? Give examples of each.
Answer:
| Biparous or dichasial cyme | Multiparous or polychasial cyme |
1. In this type of cymose inflorescence the main axis terminates into a flower and produces two lateral branches; e.g., hora, Saponaria,Mussaen da, Diant bus, etc. |
1. This is a cymose inflorescence in which the main axis is terminated by a flower and produces many lateral branches daughter axes each terminating into a flower This inflorescence looks ike an umbel but can be distinguished from umbel as here the middle flower opens first; e.g., Calotropis (madar), Viburnum, etc. |
Question 3.
Differentiate Catkin and Spadix with example.
Answer:
| Catkin (amentum) | Spadix |
| 1. It is a spike consisting of sessile, unisexual flowers. | 1. It is a spike with thick and fleshy |
2. The inflorescence axis is long and pendulous. Complete inflorescence drops altogether same time e.g., Morus (mulberry) Salix, Acalypha, etc. |
2. inflorescence axis surrounded by one or several brightly coloured bracts, called spathe; e.g., banana, maize, Colocasia, etc. |
Question 4.
Differentiate Corymb and Umbel with example
Answer:
| Corymb | Umbe |
| 1. It is a racemose inflorescence with shortened main axis. | 1.The inflorescence axis is shortened but the indivi-dual bisexual flowers are borne on pedicels of about the same length. |
| 2. The flowers have unequal stalks. | 2. Flowers are arranged in centripetal arrangement. All the flowers arise from a single point, like the ribs of an umbrella. |
3. The lower flowers have much longer pedicels than the upper ones, bringing all the flowers to more or less the same level e.g., Iberis amara (candytuft), Prunus cerasus (cherry), etc. |
3. At the base of flower stalks, there is a whorl of bracts forming the involucre e.g., Allium cepa (onion), Hydrocotyle asiatica, etc. |
Question 5.
Differentiate Hypanthodium and Spadix with example
Answer:
|
Hypanthodium |
Spadix |
| 1. Here, the inflorescence is highly reduced | It is a spike with thick and fleshy inflorescence axis surrounded by one or several brightly coloured bracts, called spathe; e.g., banana, maize, Colocasia, etc.
|
| 2. It has a cup shaped receptacle formed by the fusion of five bracts | |
| 3. On the surface of this cup, generally a yellow coloured nectar secreting gland is present. | |
| 4. A single female flower arises from the centre of the cup. | |
| 5. It is highly reduced and is borne on a long stalk. | |
6. The male flowers are highly reduced and are produced in a scorpioid manner from the axil of each |
RBSE Class 11 Biology Chapter 20 Essay Type Questions
Question 1.
Define inflorescence. Explain various types of racemose and cymose type of inflorescence with labeled diagram.
Answer:
Inflorescence:
Mode of development and arrangement of flowers on the axis is known as inflorescence. The primary stalk of the inflorescence is known as peduncle. The stalks of the individual flowers are called pedicels. Flowers with pedicels are known as pedicellate. In sorne flowers the pedicel is absent and hcy arc directK attached to the inflorescence axis such flowers arc called sessile, In solitary flowers there is no distinction between peduncle and the pedicel.
Types of InfÌorescentes:
1. Racemoseor indefrrminaie inflorescnce:
Racemose type of inflorescence, the main axis continues to grow indefinitely and is not terminated into a flower (hence the name indeterminate). It gives off flowers on lateral sides in acropetal succession, ie.. the lower or outer flowers are older than the upper or inner flowers.
2. Crmoxeor determinate brcxcence:
Cymose type of inflorescence, growth of the main axis is soon checked due to the development of a flower at its apex. Here, the main axis branches immediately below the terminal flower. These lateral branches also terminate into a flower. Terminal flower being the oldest, the development is called basipetal and order of opening of flowers is called centrifugal.
Types of Racemose or Indeterminate Inflorescence:
1. Racemose:
The inflorescence axis is simple, elongated and bears stalked, bisexual, acropetal flowers e.g., Larkspur, Brassica (Mustard), Delphinium, Crotalaria, etc
2. Panicle:
It is a modified raceme. Here the main inflorescence axis (rachis) is branched and flowers are borne acropetally on lateral branches. It is also called compound raceme; e.g., Amaltas, Gold mohur, Yucca, etc.
3. Spike: It is similar to raceme but the flowers are sessile which are attached on long peduncle acropetally; e.g., Adhatoda, Achyranthes, Piper longum, etc.
4. Compound spike (spikelet or locusta):
The inflorescence axis is branched and the flowers are arranged in a spike-like manner on the branches; e.g., Amaranthus. In grasses the unit of compound inflorescence is spikelet. Each spikelet is composed of a cluster of one or more flowers and their associated bracts.
5. Catkin (amentum):
It is a spike consisting of sessile, unisexual flowers. The inflorescence axis is long and pendulous. Complete inflorescence drops altogether same time; e.g., Morus (Mulberry) Salix, Acalypha, etc.
6. Spadix:
It is a spike with thick and fleshy inflorescence axis surrounded by one or several brightly coloured bracts, called spathe; e.g., Banana, Maize, Colocasia, etc.
7. Corymb:
It is a racemose inflorescence with shortened main axis. The flowers have unequal stalks. The lower flowers have much longer pedicels than the upper ones, bringing all the flowers to more or less the same level; e.g., Iberis amara (Candytuft), Prunus cerasus (Cherry), etc.
8. Umbel:
The inflorescence axis is shortened but the individual bisexual flowers are borne on pedicels of about the same length. Flowers are arranged in centripetal arrangement.m All the flowers arise from a single point, like the ribs of an umbrella. At the base of flower stalks, there is a whorl of bracts forming the involucre; e.g., Allium cepa (Onion), Hydrocotyle asiatica, etc.
9. Compound umbel:
It is a modified umbel where inflorescence axis is branched; the branches arise from a single point in exactly umbel-like manner. These branches bear umbels which are known as umbellules. The bract present at the base umbellules is called Involucre and a bract present at the base of pedicel is called Involucel; e.g., Coriandrum (Coriander) Foeniculum (Fennel), Daucus carota (Carrot) and other members of Umbelliferae.
10. Capitulum or head (Anthodium):
In this type the inflorescence axis is flattened forming a more or less convex disc, called receptacle. A large number of sessile flowers (called florets) are borne on the receptacle in centripetal manner. Centrally placed florets are called Disc florets while peripheral florets are called Ray florets. The whole inflorescence is surrounded by one or more whorls of bracts forming involucre; e.g., Sunflower, Marigold, (all members of Compositae).
11. Capitate:
In this type a large number of sessile flowers arise from a suppressed axis forming a globose structure; e.g., Acacia, Mimosa. It differs from capitulum in the absence of receptacle.
Types of Cymose or Determinate Inflorescence:
Solitary:
When only flower is present on floral axis. On the basis of position of flower it may be of two type
- Solitary axillary: e g., China rose
- Solitary terminal: e.g., Rose, Argemone
1. Uniparous or monochasial cyme:
This is a cymose inflorescence where the main axis terminates into flower and produces only one lateral branch which also terminates into a flower. Depending upon the sequence of lateral branches uniparous cyme is of following two types.
2. Scorpioid cyme (cincinnus or rhinidiuml):
A uniparous cyme in which the successive lateral branches develop on alternate sides in a zig-zag manner is called scorpioid cyme; e.g., Ranunculus bulbosus, Heliotropium, etc. This is a uniparous cyme in which the lateral branches develop successively on the same side forming a sort of helix; e.g., Begonia, Juncus, etc
3. Helicoid cyme:
This is a uniparous cyme in which the lateral branches develop successively on the same side forming a sort of helix; e.g., Begonia, Juncus, etc.
4. Biparous or dichasial cyme:
In this type of cymose inflorescence the main axis terminates into a flower and produces two lateral branches; e.g., Ixora Saponana.Mussaencla, Dianthus, etc.
5. Multiparous or polychasial cyme:
This is a cymose inflorescence in which the main axis is terminated by a flower and produces many lateral branches (daughter axis), each terminating into a flower. This inflorescence looks like an umbel but can be distinguished from umbel as here the middle flower opens first e.g.,Calotropis (Madar), Viburnum, etc.
Question 2.
Explain special type of inflorescence with labeled diagrams.
Answer:
special type of inflorescence: The following are some of the special types of inflorescences.
1. Hypanthodium:
Here, the inflorescence is highly reduced. It has a cup shaped receptacle formed by the fusion of five bracts. On the surface of this cup, generally a yellow coloured nectar secreting gland is present. A single female flower arises from the centre of the cup. It is highly reduced and is borne on a long stalk. The male flowers are highly reduced and are produced in a scorpioid manner from the axil of each bract; e.g. Ficus (Banyan) and Fig tree.
2. Cyathium:
It is a,compound inflorescence which looks like a single flower. The peduncle terminates into a single female flower. It is surrounded by a large number of male flowers arranged in scorpioid cyme. The female flower is represented by only a single tricarpellary and syncarpous gynoecium. Each male flower consists of a single stalked stamen. Male flower borne in axis of a scaly bract. Whole inflorescence is enclosed within a cup shaped involure which is often glandular e.g., Euphorbia.
3. Verticillaster:
It is characterstics of family Labiate. It is a dhasial cyme which is reduced to two scorpioid cyme , one on each side of the nodes of inflorescence axio. Tire inflorescence axis consists of a series of nodes. At each node there are two opposite bracts. In the axil of each bract there is a dichasial cyme, i.e., the main axis terminates in to one large flower and forms two lateral branches which also terminate into two flowers. After this stage it changes into monochasial cyme. Flowers are sessile or sub – sessile, e.g., Ocimum, Mentha, Leucas etc.
