RBSE Solutions Class 11 Biology Chapter 32 Grades of Body Organisation

RBSE Class 11 Biology Chapter 32 Multiple Choice Objective Questions

Question 1. Animals of phylum protozoa exhibit :
(a) Cellular grade
(b) Protoplasmic grade
(c) Tissue-organ grade
(d) Organ-system grade
Answer: (b) Protoplasmic grade
In simple words: Animals like protozoa have a very simple body plan. All their life functions happen within a single cell's protoplasm.

🎯 Exam Tip: Remember that Protozoa are single-celled organisms, so their organization level is at the most basic cellular (protoplasmic) level.

Question 2. Basis of Classification of animals into protozoa and metazoa is :
(a) Symmetry
(b) Cleavage
(c) Number of cells
(d) Body shape
Answer: (c) Number of cells
In simple words: Protozoa are single-celled animals, while metazoa are multicellular animals. The number of cells is the main difference.

🎯 Exam Tip: Protozoa means "first animals" and are unicellular, whereas Metazoa refers to all multicellular animals, clearly showing that cell count is the fundamental distinction.

Question 4. Body organisation in human being is :
(a) Organ-System level
(b) Tissue-Organ level
(c) Cell-Organ level
(d) Cell-Tissue level
Answer: (a) Organ-System level
In simple words: Humans have a very complex body structure. Different organs work together to form systems, like the digestive or circulatory system.

🎯 Exam Tip: For complex organisms like humans, the highest level of organization is always the organ-system, where multiple organs cooperate for major bodily functions.

Question 5. The grade of organisation in tape worm is :
(a) Tissue-Organ
(b) Organ-System
(c) Protoplasmic
(d) Cellular
Answer: (a) Tissue-Organ
In simple words: Tapeworms are more complex than simple cells but less complex than animals with full organ systems. They have tissues that group together to form simple organs.

🎯 Exam Tip: Organisms like flatworms (Platyhelminthes), which include tapeworms, typically exhibit the tissue-organ grade, meaning they have organized tissues forming basic organs but not integrated organ systems.

RBSE Class 11 Biology Chapter 32 Very Short Answer Questions

Question 1. Which perform vital activities in the protozoan?
Answer: In protozoans, small parts inside the cell called cell organelles perform all the important life activities. These organelles are like tiny organs for the single cell.
In simple words: Cell organelles do all the important work in a protozoan.

🎯 Exam Tip: Remember that unicellular organisms lack tissues and organs, so cell organelles are crucial for all metabolic functions.

Question 2. Give example of protoplasmic grade of organisation.
Answer: Examples of organisms with protoplasmic grade of organisation include Amoeba and Paramecium. In these single-celled organisms, all life processes occur within the protoplasm itself, making it the most basic level of organization.
In simple words: Amoeba and Paramecium are examples. Their whole body is just one cell, and everything happens inside it.

🎯 Exam Tip: Protozoa, such as Amoeba and Paramecium, are classic examples of protoplasmic organization where the entire organism is a single cell performing all functions.

Question 4. Performation of any function by a group of organs is an example of which body organisation?
Answer: The performance of a function by a group of organs is an example of organ-system grade of organisation. This is the highest level of organization, where multiple organs work together to carry out a specific life process.
In simple words: When many organs work together for one job, it's called organ-system organization.

🎯 Exam Tip: Recognize that "organ-system grade" implies a division of labor where various organs contribute to complex functions like digestion or circulation.

Question 5. Which type of body organisation is found in phylum cnideria?
Answer: Phylum Cnidaria, which includes animals like jellyfish and sea anemones, exhibits cell-tissue grade of organisation. Here, cells are grouped into tissues to perform specific functions, but they don't form true organs or organ systems yet.
In simple words: Cnidarians have a cell-tissue type of body organization.

🎯 Exam Tip: Cnidarians represent the first group in animal evolution to have true tissues, making them a key example of the cell-tissue grade of organization.

RBSE Class 11 Biology Chapter 32 Short Answer Questions

Question 1. What do you mean by organ system grade of organisation?
Answer: Organ-system grade of organisation is a level where different organ systems are formed to carry out specific functions in an organism. For example, the alimentary canal and digestive glands together form the digestive system to help digest food. Similarly, there are respiratory, excretory, and reproductive systems. This advanced type of organisation is found in animals from phylum Aschelminths all the way up to phylum Chordata, including humans. This allows for complex and efficient functioning of the body.
In simple words: Organ-system grade means different body parts, like the stomach and intestines, work together as systems for big jobs such as digestion. This is seen in more complex animals.

🎯 Exam Tip: When defining organ-system grade, always give specific examples of systems (e.g., digestive, respiratory) and mention the range of phyla where it is observed.

Question 2. Write the salient features of body organisation in the animals of phylum cnederia.
Answer: The body organisation in animals of phylum Cnidaria is also known as "low grade of tissue organisation" or cell-tissue grade. In these animals, definite tissues and organs are not fully formed. Instead, distinct layers of cells are organised into simple tissues. This means cells that do similar jobs are grouped together, but they do not form complex organs like in higher animals. This type of organisation is characteristic of animals found in the phylum Coelenterata (Cnidaria). They show a clear step up from single-celled organisms, demonstrating the beginnings of specialized cell groups.
In simple words: Cnidarians have simple tissue organization. They don't have complex organs, but their cells form distinct layers to do different jobs.

🎯 Exam Tip: Key features of Cnidarian body organization include the presence of tissue layers (diploblastic) and the absence of true organs or organ systems.

Question 3. Write the grades of body organisation as per evolutionary sequence.
Answer: The grades of body organisation, from simplest to most complex in evolutionary sequence, are:
1. Protoplasmic Grade of Organisation
2. Cellular Grade of Organisation
3. Cell-Tissue Grade of Organisation
4. Tissue-Organ Grade of Organisation
5. Organ-System Grade of Organisation
Each step shows an increasing level of cell specialisation and coordination, leading to more complex animal forms.
In simple words: Body organization started very simply and became more complex over time. It began with protoplasmic, then cellular, then cell-tissue, then tissue-organ, and finally organ-system levels.

🎯 Exam Tip: Listing the grades in the correct evolutionary order is crucial; remember the progression from single-celled functions to complex system integration.

Schematic Demonstration of Grades of Body Organisation

Question 4. Differentiate protoplasmic and cellular grades of organisation.
Answer:
Protoplasmic Grade of Organisation: This grade is found in members of phylum Protozoa. Their body consists of a single cell, and all essential life activities are carried out within the protoplasm using various cell organelles. Therefore, it is known as "protoplasmic grade of organisation." The division of labor, or specialized tasks, occurs among the cell organelles themselves. For example, in an Amoeba, the contractile vacuole handles water balance, and pseudopods help with movement and feeding.

Cellular Grade of Organisation: Sponges (phylum Porifera) show this grade of organisation. Their body is multicellular, meaning it has many cells, but these cells are not identical. They are specialized to perform specific functions, like pinacoderm cells for the outer layer and choanoderm cells for feeding. True tissues and organs are absent. However, the cells do show division of labor, where different cells have different jobs. This is why their body organization is called a cellular grade of organization, marking a step up from unicellular forms.
In simple words: Protoplasmic grade is when one cell does everything (like in protozoa). Cellular grade is when an animal has many cells, but they are not fully organized into tissues or organs (like in sponges).

🎯 Exam Tip: When differentiating, focus on the number of cells, the presence of tissues, and how labor is divided (within organelles vs. among specialized cells).

Question 5. Explain the basis of grades of body organisations in animals.
Answer: The basis of grades of body organisation in animals depends on how cells are structured and arranged to perform different functions. In simpler animals, cells might work individually, but in higher animals, cells come together to form tissues. These tissues then group to create organs, and multiple organs work together to form organ systems. This increasing complexity, from cells to systems, defines the different grades of organization, allowing for more specialized and efficient life processes. This progression reflects the evolutionary path animals have taken over millions of years.
In simple words: Body organization levels are based on how cells arrange themselves. Cells combine to make tissues, tissues make organs, and organs make systems, creating different levels of complexity in animals.

🎯 Exam Tip: Emphasize the hierarchy: cells forming tissues, tissues forming organs, and organs forming organ systems as the fundamental basis for classifying body organization grades.

Question 6. Draw a schematic diagram to exhibit various levels of body organisation.
Answer: The schematic diagram below illustrates the various levels of body organisation, from the simplest to the most complex, found in the animal kingdom. It shows how increasing complexity leads to more specialized structures and functions. This visual representation helps understand the evolutionary path of animal body plans.

🎯 Exam Tip: When drawing or describing, ensure the arrows correctly indicate the progression from simpler to more complex grades and that representative phyla are associated with each grade.

RBSE Class 11 Biology Chapter 32 Essay Type Questions

Question 1. What do you mean by grade of body organisation. Explain types of body organisation with examples.
Answer: Grade of body organisation refers to the level of complexity and differentiation in the body structure of animals. It describes how cells, tissues, organs, and organ systems are arranged to perform various functions. As animals evolved, their body plans became progressively more complex. This classification helps us understand the evolutionary relationships and functional capabilities of different animal groups. The main types are:

1. Protoplasmic Grade of Organisation: This is the simplest level, found in single-celled organisms like those in phylum Protozoa (e.g., Amoeba, Paramecium). All vital life activities, such as feeding, movement, and reproduction, are carried out within the protoplasm of a single cell. Specialized tasks are handled by different cell organelles within that cell. This grade represents the most fundamental form of life.

2. Cellular Grade of Organisation: This grade is seen in multicellular but very simple animals, such as sponges (phylum Porifera). Here, cells are numerous and specialized to perform different functions (e.g., pinacoderm, choanoderm cells), but they are not organized into true tissues or organs. There is a division of labor among different cell types, but they mostly function independently, and there is minimal coordination between them. The cells cooperate but don't form tightly bound tissues.

3. Cell-Tissue Grade of Organisation: This level is found in phylum Cnidaria (e.g., jellyfish, sea anemones). In these animals, cells that perform similar functions are grouped together to form definite tissues. However, the organization does not extend to the formation of complex organs. Distinct cell layers are present, but a true organ-level complexity is absent. It represents an important evolutionary step where cells begin to work as coordinated units.

4. Tissue-Organ Grade of Organisation: This grade is characteristic of phylum Platyhelminthes (flatworms). Here, tissues are further organized to form simple organs, like eyespots and reproductive organs. These organs work together to perform specific functions. While more complex than cell-tissue grade, a full organ-system integration, where multiple organs cooperate extensively, is not yet present. This allows for more efficient performance of complex tasks than just tissues alone.

5. Organ-System Grade of Organisation: This is the highest and most complex level of organisation, found in most higher animals, ranging from phylum Aschelminths to phylum Chordata (which includes humans). In this grade, different organs are grouped together to form functional organ systems, such as the digestive system (alimentary canal and digestive glands), respiratory system, excretory system, and reproductive system. Each system is specialized to perform a major life process, and all systems work in a highly coordinated manner, enabling complex behaviors and high metabolic efficiency. This level supports large body sizes and sophisticated internal environments.
In simple words: Body organization is about how animals are built, from simple single cells to complex body systems. There are different levels: protoplasmic (one cell does all), cellular (many cells with different jobs but no true tissues), cell-tissue (cells form simple tissues), tissue-organ (tissues form basic organs), and organ-system (many organs work together as systems, like digestion). Each level is more complex than the last.

🎯 Exam Tip: For essay questions, define 'grade of organisation' first, then systematically explain each type with a clear example and a defining characteristic that differentiates it from the previous level. Showing the evolutionary progression is key.