Kingdom Prokaryotae (Monera)

 Biology XI Notes

Kingdom Prokaryotae (Monera) - Short Questions Answers

Chapter # 06
Biology - XI
Section III - Biodiversity

Kingdom Prokaryotae (Monera)

Q.1: What are Bacteria? What are the types of Bacteria?

Ans: Bacteria:
Bacteria are the simplest and smallest living organisms which possess cellular structure. They are microscopic. They were discovered by a Dutch scientist Anton Von Leeuwenhoek in 1676, then he gave them the name bacteria in 1683.

Some microbiologists have placed bacteria in two groups:

• Eubacteria:
  It is a large division. These bacteria are the true bacteria.
• Archaebacteria:
  It is a smaller division. These are ancient bacteria.

![Types of Bacteria]
(Illustration showing different types of bacteria: Coccus, Bacillus, and Spiral)

The size of bacteria is very small, ranging from 0.5 microns to 2 microns. They are found everywhere, in soil, water, and air. They do not have chlorophyll, so they live as parasites in plants and animals or saprophytes on dead organic substances.

Q.2: Describe the structure of Ulva?

Ans: Ulva belongs to the green algae. It grows in marine water and is considered a primitive plant in the group. It is also known as sea-lettuce. Its body is called thallus, which consists of erect broad sheet-like branches, or blades. From the base of the plant, thread-like colorless structures are given out which help in the attachment of the plant to any rock or stone and thus act like a hold-fast. The hold-fast does not absorb water.

The body of Ulva is composed of two layers of cells. The outer layer has contact with water, while the inner layer is prevented from the water contact. The cells are elongated. Each cell contains cytoplasm, a nucleus, and a single cup-shaped chloroplast.

Q.3: Describe the life cycle of Ulva with alternation of generations?

Ans: Life-Cycle of Ulva:
The life cycle of Ulva is completed in two stages. The first stage is gametophyte, in which the male and female gametes are produced by separate plants. These gametes unite together to form a zygote. The zygote develops into a sporophyte, which is the second stage of the life cycle. The sporophyte forms spores which produce gametophyte again. This whole process of the life cycle is called alternation of generations. In Ulva, gametophyte and sporophyte plants are similar in structure, so this process is termed as isomorphic alternation of generations. The life cycle is described as follows:

Gametophytic Stage:
In this stage, sexual reproduction takes place, and two types of male and female gametes are formed. The male and female plants are separate but similar in structure. The male plant produces male gametes, and the female plant produces female gametes. These male and female gametes are externally similar and...

(The diagram illustrates the life cycle of Ulva, including stages such as gametophyte, fertilization, diploid zygote, diploid sporophyte, meiosis, and zoospores.)

Internally different, they are called isogametes. They come in water and fuse together to form zygote. The zygote is diploid and it contains 26 chromosomes. It germinates into sporophyte which is also diploid in nature.

Sporophytic Stage:
It is the second stage of the life cycle of Ulva. It is developed by the germination of zygote. The sporophyte resembles the gametophyte in structure. The sporophyte produces zoospores by asexual reproduction. In the formation of zoospores, meiosis takes place due to which they become haploid and contain 13 chromosomes. The zoospores become free after maturation. Half of the zoospores form male and half produce female gametophyte of Ulva plant. In this way, its life cycle is completed.

Q.4: Describe the structure of Euglena?

Ans: Euglena is a microscopic unicellular living organism. It is found in fresh water. It is considered as an animal and as well as a plant because it has the properties of both. It is plant-like because it has chlorophyll. It is animal-like because it has no cell wall and is motile.

Shape and Structure:
Euglena is microscopic in nature. It has an elongated body. Its upper end is blunt and lower end is pointed. Around the body, a covering is present, called pellicle. Inside the body, cytoplasm is present which consists of two parts, outer ectoplasm and inner endoplasm. Ectoplasm is more viscous than endoplasm.
In the cytoplasm, many plate-like bodies are found, called chloroplasts. They contain green color and perform the function of manufacturing the food material, so Euglena can manufacture its own food material like plants with the help of chlorophyll. In the center of the body, the nucleus is present which contains a small nucleolus. The nucleus controls all the functions of the body.

Mouth:
At the upper end of the body, a funnel-shaped depression is present, called mouth or cytostome. The mouth opens into the gullet which leads into another structure, called reservoir. Near to the reservoir, one or few contractile vacuoles are present which help in the excretion of harmful substances and water. The contractile vacuoles open into the reservoir. The mouth and gullet are not used for feeding but they are used only for excretion. Water and other waste materials are removed from the body in this process.

Movement:
In Euglena, movement takes place by a long thread-like body, called flagellum. It arises from the upper part of the reservoir. Near the reservoir, a reddish body is also found, called eyespot. It is very sensitive to light. The animal moves to a place with the help of flagellum where suitable light is present.

Taxonomic Position of Euglena:
Euglena is an example of Eukaryotes. It contains certain characters of plants as well as animals.

Q.5: Describe the structure of Slime Mold?

Ans: Slime molds are fungi-like protists. They form a special group of organisms, which are animal-like in their body structure and plant-like in their reproduction.

Slime molds are creeping multinucleate masses of cytoplasm, looking like egg white. They grow rapidly up to one foot in damp and shady places, crawl over grasses, decaying leaves, old and rotten logs of wood. They may be colorless and sometimes contain different colors like orange, red, brown, or violet. They do not contain chlorophyll and live as saprophytes.

Structure:
The body of slime mold consists of an irregularly shaped mass of protoplasm, which is naked, i.e., has no proper body wall. The naked protoplasm is bounded by a non-cellular, thin, flexible slimy layer. Due to the presence of this slime layer, it is called a slime mold. Within the slime layer, protoplasm also contains a plasma membrane. Slime mold has no proper shape and size. The protoplasm consists of outer ectoplasm and inner endoplasm. The protoplasm contains many diploid nuclei. This body of slime mold is called plasmodium. It produces pseudopodia and shows amoeboid movement, so it seems to be like a giant amoeba. By the help of pseudopodia, it engulfs and digests bacteria and food particles, so it also contains food vacuoles and undigested food particles in the cytoplasm.

Q.6: Describe the life cycle of Slime Mold?

Ans: Life Cycle of Slime Mold (Plasmodium):
In the life cycle of slime mold, there are two types of reproduction:

• Asexual reproduction
• Sexual reproduction

Asexual Reproduction:
In slime mold (Plasmodium), asexual reproduction takes place by sporangia or fruiting bodies. These are produced in dry and warm weather. At the time of reproduction, the slime mold comes out of darkness and moves to exposed places which are dry.

The sporangia are developed on small stalks. These sporangia are small and golf-ball-like structures. The sporangia are of different colors. In the sporangium, many rounded spores are produced. Each spore is uninucleate and covered by a thick spiny wall. In the formation of spores, meiosis occurs, so haploid spores are formed. The spores are liberated out, and spores are dispersed by wind or rain to other places.

Germination of Spore:
The spore germinates on moist dead leaves, logs, or soil. From the spore, a tiny spindle-shaped structure comes out, called swarm spore or swarm cell.

(Illustration labeled as Fig. 7-6: "Slime molds. Pictorial life cycle of Physarum polycephalum" showing the stages of spore germination, meiosis, myxamoebae formation, plasmogamy, karyogamy, zygote formation, and development into young plasmodium and sporangium.)

From each spore, one to four swarm cells may be produced. The swarm spores are naked and biflagellate; one flagellum is long and one is short. The swarm spores are uninucleate and amoeboid.

• Myxamoeba:
  Sometimes instead of swarm cells, one to four amoeboid cells are produced from the spores, called myxamoebae. These are formed in dry conditions. These myxamoebae divide and form many myxamoebae.

Sexual Reproduction:
In slime mold, both swarm cells and myxamoebae may behave as gametes. They take part in sexual reproduction.

The swarm cells are fused together by their posterior ends. By their fusion, a zygote is formed, which is binucleate and flagellate. By the help of flagella, it swims for a short time, then it loses its flagella. The two nuclei of it fuse together to form a diploid nucleus.

The myxamoebae which come out of spores may also fuse together to form a zygote.

The diploid nucleus of the zygote, produced by swarm cells or myxamoebae, divides by mitosis and forms many nuclei; then, by gradual process, it grows into a new plasmodium.

Q.7: Describe the structure of Phytophthora and symptoms of the disease late blight of Potato?

Ans: Phytophthora (Late Blight of Potato)
Phytophthora infests and causes a disease in potato and tomato, called late blight.

Structure:
The body of Phytophthora is known as mycelium. It is branched and composed of many thread-like structures, called hyphae. The mycelium is unseptate. In the mycelium, cytoplasm is present, which has many nuclei. Due to the unseptate and multinucleate condition, it is called coenocytic mycelium. The mycelium is intercellular or intracellular and absorbs food material from host cells by haustoria.

Symptoms:
This disease is visible after flower formation. Due to the disease, many black or bluish-brown spots are produced on the leaves, which increase their size and ultimately cover the whole leaf. Later on, the tubers are affected. Their skin turns brown, and tissues become very soft.

Q.8: Describe the Asexual Reproduction of Phytophthora?

Ans: Asexual Reproduction:
In this reproduction, zoospores are produced in reproductive organs, called sporangia. At the time of reproduction, many erect branches arise from mycelium, called sporangiophores; they come out of the stomata of lower epidermis of host leaves. They produce more branches, at the tips of which oval or lemon-shaped sporangia are formed.

(Fig. 7-7(B): Asexual Reproduction in Phytophthora)

Each sporangium produces eight biflagellate zoospores. After maturation, it ruptures and all the spores become free. During favorable conditions, each zoospore forms a germ tube. It enters the host leaf through stomata or cuticle and produces new mycelium of Phytophthora.

Q.9: Describe the Sexual Reproduction of Phytophthora?

Ans: Sexual Reproduction:
In Phytophthora, sexual reproduction is of oogamous type. In this method, two entirely different types of male and female reproductive organs are produced; males are antheridia and females are the oogonia.

• Fertilization:
  At the time of fertilization, the male nucleus migrates into the oogonium; the male and female nuclei are fused together to form an oospore.

• Germination of Oospore:
  At the time of germination, the oospore forms a germ-tube. At the tip of the germ tube, a sporangium is formed, which produces many spores. When the spores are mature, the wall of the sporangium ruptures and the spores are released.

• (Fig. 7.8: Sexual Reproduction in Phytophthora)

  The sporangium ruptures and all the spores come out. During favorable conditions, they germinate into new mycelium of Phytophthora.

Q.10: Distinguish between the following?

Ans: Sexual Ulva and Asexual Ulva:

Sexual Ulva	Asexual Ulva
Sexual Ulva is gametophyte.	Asexual Ulva is sporophyte.
It is haploid, contains 13 chromosomes.	It is diploid, contains 26 chromosomes.
It produces male and female gametes by mitosis. Male and female Ulva are separate	It produces spores by meiosis.
Fertilization takes place in the reproductive stage of sexual Ulva. Q.11: Describe the Important Characters of Phylum Protozoa? Ans: Important Characters of Phylum Protozoa: They are microscopic; their body consists of only one cell. They live singly or in groups. They are rounded, oval, elongated, or irregular in shape. The protoplasm consists of outer ectoplasm and inner endoplasm. A definite nucleus is present in the body. Respiration takes place through the external surface or by diffusion. The movement occurs by pseudopodia, cilia, or flagella. Reproduction is by simple cell-division or by sexual method. During unfavorable conditions, some protozoans form non-motile spores or cysts, covered by a thick layer. When favorable conditions return, the spores are liberated out and develop into new animals. Some protozoans live as parasites in the bodies of animals and plants. Q.12: Write down the names of Classes of Phylum Protozoa? Ans: The Phylum Protozoa is divided into the following classes: Class — Mastigophora or Flagellata Class — Rhizopoda or Sarcodina Class — Ciliata Class — Suctoria Class — Sporozoa Q.13: What are the characters of Class Mastigophora (Flagellata)? Ans: Class - Mastigophora or Flagellata: The shape of the body does not change. It remains constant. They live singly or in colonies. The body is covered by an outer covering, called Pellicle. It is elastic. Sometimes a shell is also present around the body, which is made up of cytoplasm, chitin, or cilia. Ectoplasm and endoplasm cannot be clearly separated from each other. A nucleus is present. From the outer surface of the body, one or more thread-like bodies are developed, called flagella. They help in locomotion. Reproduction takes place by asexual or sexual methods. In class Flagellata, there are two types of animals. (Fig. 7-9: Euglena illustration showing flagellum, mouth, pharynx, eyespot, reservoir, contractile vacuole, chloroplast, nucleus, nucleolus, and other parts.) With Chlorophyll: They live in fresh as well as in marine water. They have chlorophyll and manufacture their food like plants. e.g. Euglena - It lives single. Volvox - It lives in the form of a colony. Noctiluca - It lives in the sea. It emits light. Without Chlorophyll: They do not have chlorophyll. They are usually parasites. e.g. Trypanosoma and Leishmania. They live as parasites in the body of vertebrates. (Fig. 7-10: Volvox; Fig. 7-11: Trypanosoma) Q.14: What are the characters of Rhizopoda? (Sarcodina) Ans: Class Rhizopoda or Sarcodina: They have a very soft body wall, which can change the shape of the body. In some animals, the body is covered by a shell. e.g. Globigerina. From their outer surface, pseudopodia are produced, which help in locomotion and to capture the food. The protoplasm is divided into ectoplasm and endoplasm. Nucleus is one or more. Excretion takes place by contractile vacuole. In marine animals, contractile vacuole is absent. e.g. Amoeba, Heliozoans, Foraminiferans, Globigerina. (Fig. 7-12: Amoeba) Q.15: What are the characters of Class Suctoria of Phylum Protozoa? Ans: Class - Suctoria: These animals have a close relationship with ciliate animals, and they seem to have evolved from them. Their characters are as follows: They have cilia which help in swimming, but the adult animals are without cilia. They are attached to any solid object by the help of a long rod-like structure. They contain two types of nuclei, micronucleus (smaller) and mega nucleus (large). From their body, certain thin structures are developed, called tentacles. (Fig. 7-13: Acineta (Suctoria)) Q.16: What are the characters of Class Ciliata of Phylum Protozoa? Ans: Class - Ciliata: Their body is provided with cilia, which help in locomotion and to get food into the body. They have a mouth, through which the food enters the body. The food may also be taken through the general surface. They contain two nuclei, micronucleus and macronucleus. Body is covered by pellicle. Excretion takes place by contractile vacuole. e.g., Paramecium, Stentor, Vorticella. (Fig. 7-14: Paramecium) Q.17: What are the characters of Class Sporozoa of Phylum Protozoa? Ans: Class - Sporozoa: The animals of this class are usually parasites. They do not produce special organs for locomotion. They perform very slow movement, called amoeboid movement. They contain cytoplasm and nucleus. Reproduction takes place by asexual and sexual methods. They cause some dangerous diseases in man and other vertebrates, such as malaria by Plasmodium. Their life cycle is completed in the body of two hosts: one is the body of a vertebrate, and the other is the body of an invertebrate. The plasmodium is transferred into the body of man from the body of a female Anopheles mosquito. Q.18: Describe the Life Cycle of Plasmodium in the body of man? Ans: Life Cycle of Plasmodium in the Body of Man: (Asexual Cycle - Schizogony) When a female Anopheles mosquito bites a healthy person, it transfers its sporozoites into the blood of man. The sporozoites are very small spindle or sickle-shaped bodies. They contain cytoplasm and nucleus. In man, the life cycle of Plasmodium consists of four phases. Pre-erythrocytic Stage: After some time, these sporozoites are transferred from the blood to the liver cells. Each sporozoite enters a liver cell and lives as a parasite. It becomes rounded in shape and is called a cryptozoite. The cryptozoite uses liver cell as its food material. Schizogony in Liver Cells: In liver cells, each cryptozoite starts multiplication. It divides by a simple process called schizogony. By this process, it produces many small bodies called merozoites. These merozoites become free by rupturing the liver cell. Each merozoite enters a new liver cell and behaves as a cryptozoite; it starts the same process again. In this way, two or three times schizogony process is completed in liver cells. Erythrocytic Stage (Trophozoite Stage): After some time, some of the merozoites or cryptozoites are transferred into the bloodstream. Each body enters a Red Blood Corpuscle (RBC). In RBC, the cryptozoite or merozoite is now known as trophozoite. In RBC, the trophozoite shows certain changes which are as follows: Ring Like Stage: In trophozoite, a vacuole appears and its nucleus transfers to the margin, so it becomes ring-shaped; this stage is called Ring Stage. Amoeboid Stage: After some time, the vacuole disappears, the nucleus comes back in the center, and from the outer surface of trophozoite, finger-like pseudopodia are produced. It becomes amoeba-shaped; this stage is called Amoeboid Stage. Schizont Stage: After some time, pseudopodia of trophozoite disappear, and it is converted into a rounded structure. Now it is ready to multiply by schizogony process; it is called Schizont. The schizont divides into many bodies known as Merozoites. The merozoites become free by rupturing the outer layer. These merozoites enter new RBCs; now each merozoite acts as a trophozoite and repeats the schizogony process once again. In this way, two or three times this process is repeated in RBCs of man. Post-Erythrocytic Stage: From the RBCs, some merozoites are again transferred into the liver cells and start schizonic reproduction; it is called post erythrocytic stage. Gametogony (Formation of Gametocytes): When schizogony is completed many times in the blood of man, then instead of forming merozoites, another type of bodies are produced, known as Gametocytes. Now it is necessary that these bodies should be transferred into the body of a female Anopheles mosquito. In the body of man, the life cycle of Plasmodium is completed. Q.19: Describe the stages of Life Cycle of Plasmodium in Mosquito? Ans: Stage of Life Cycle of Plasmodium in the Body of Female Anopheles Mosquito: (Sexual Cycle in Mosquito) The sexual cycle of Plasmodium is completed in the stomach of female Anopheles mosquito. In this cycle, the following stages are present. Gametogony (Formation of gametes) Syngamy (Fusion of gametes) Sporogony (Formation of sporozoites) When a female Anopheles mosquito bites a malaria patient and sucks his blood, along with blood gametocytes, schizonts, merozoites are transferred into the body of mosquito. In the body of mosquito only gametocytes remain alive and active, while other bodies are destroyed by the action of enzymes of stomach. (Fig. 7-15: Lifecycle of Plasmodium (Malaria Parasite) - Illustration showing various stages including Infection of Corpuscle, Ring Stage, Amoeboid Stage, Trophozoite, Schizogony, Gametocyte formation, Ookinete, Oocyst formation, and Sporozoite development in the mosquito's body) The gametocytes are of the types: Micro-gametocytes Macro-gametocytes Gametogony (Formation of Male and Female Gametes): Microgametocytes are smaller in size. Each micro-gametocyte produces many male gametes from its outer surface. These male gametes are thread-like structures; after maturation, these are separated from micro-gametocyte and move towards female gamete to take part in fertilization. Macro-gametocytes are larger in size. Each macro-gametocyte develops into a single female gamete, called oocyte. It has a small part at one side, known as the reception cone. Syngamy (Fertilization): The fusion of two male and female gametes is called syngamy. At the time of fertilization, many male gametes move towards the female gamete, but only one male gamete is attached with the reception cone, its nucleus is transferred into the female gamete, and by the fusion of two nuclei, a zygote is formed. Sporogony (Germination of Zygote and Formation of Sporozoites): After some time, the zygote starts germination. It develops into a worm-like structure called ookinete. The ookinete then changes into a rounded structure, known as oocyst. It is also covered by a protective covering. In the oocyst, many bodies are produced by the process of division. These are called sporoblasts. Each sporoblast produces many thread-like structures from its outer surface, called sporozoites. These sporozoites become free after some time, and then they are stored in the salivary glands of the mosquito. When this female Anopheles mosquito bites a healthy person, the sporozoites are transferred into his body, and hence malaria can be started once again. Q.20: What are the symptoms and precautions/treatment of Malaria? Ans: Symptoms of Malaria: The symptoms of malaria appear after many days of infection. The period of the parasite in the body before symptoms is called the incubation period. The symptoms of malaria are fever with shivering, vomiting or feeling of vomiting, loss of appetite, constipation, then headache, pain in the muscles and joints. In malaria, the fever may be up to 106°F, there are shaking chills and seating. Precautions and Treatment: Mosquitoes should be killed, which are the cause of malaria. There should not be stagnant water places anywhere because the mosquitoes lay their eggs in stagnant water. In case of malaria, anti-malarial drugs should be used. Q.21: Distinguish between the following? Ans: Flagellata and Sarcodina: Flagellata Sarcodina It is the class of Phylum Protozoa, the animals of this class contain one or two flagella, which help in locomotion. The animals of this class do not contain flagella. Their locomotory organs are called pseudopodia. Their body has a particular shape; it is not changed. They have an irregular shape of body. It can be changed regularly. They have fast locomotion, called Flagellary locomotion. They have slow locomotion, called amoeboid locomotion. Some members contain chlorophyll, i.e., they are autotrophs, and some are parasites. e.g., Euglena, Trypanosoma They do not contain chlorophyll. e.g., Amoeba