Samacheer Kalvi 9th Science Solutions Chapter 18 Pdf
Tamilnadu Board Samacheer Kalvi 9th Science Solutions Chapter 18: Tamilnadu State Board Solution Class 10 Science Chapter 18 – Organization of Tissues.
Samacheer Kalvi 9th Science Solutions Chapter 18: Overview
|
Board |
Samacheer Kalvi |
| Class |
9 |
|
Subject |
Science |
| Chapter |
18 |
|
Chapter Name |
Organization of Tissues |
Samacheer Kalvi 9th Science Solutions Chapter 18 Organization of Tissues
Exercise:
I.Choose the correct answer.
1.) The tissue composed of living thin walled polyhedral cell is
a) parenchyma
b) pollenchyma
c) pclerenchyma
d) None of above
Ans: a. parenchyma
Explanation: Because, parenchyma are simple permanent tissues composed of living cells.
2.) The fibres consists of
a) parenchyma
b) sclerenchyma
c) collenchyma
d) None of above
Ans: b. sclerenchyma
Explanation: Because, sclerenchymatous cells associated with primary and secondary phloem are called as phloem fibers.
3.) Companion cells are closely associated with
a) sieve elements
b) vessel elements
c) trichomes
d) guard cells.
Ans: a. sieve elements
Explanation: Because, the companion cells may be equal in length to the accompanying sieve tube element.
4.) Which ofthe following is a complex tissue?
a) Parenchyma
b) Collenchyma
c) Xylem
d) Sclerenchyma
Ans: c. Xylem
Explanation: Because, xylem and phloem are only the examples of complex tissues which are made of more than one type of cells.
5.) Aerenchyma is found in
a) epiphytes
b) hydrophytes
c) halophytes
d) xerophytes
Ans: b. hydrophytes
Explanation: Because, in aquatic plants parenchyma possesses intercellular spaces which are called as aerenchyma.
6.) Smooth muscles occur in
a) uterus
b) artery
c) vein
d) All of the above.
Ans: a. uterus
Explanation: Because, the internal organs such as uterus contains smooth muscles for contraction and relaxation in pregnancy.
7.) Nerve cell does not contains
a) axon
b) nerve endings
c) tendons
d) dendrites
Ans: c. tendons
Explanation: Because, nerve cells contains axon, nerve endings and dendrons.
Match the following.
Ans:
Sclereids: Sclerenchyma
Chloroplast: Chlorenchyma
Simple tissue: Collenchyma
Companion cell: Phloem
Trachieds: Xylem
III. Fill in the blanks.
1.) ——-Tissues provide mechanical support to organs.
Ans: Collenchyma tissues provides mechanical support to organs.
Explanation: Because, collenchyma are the simple tissues which possesses thick primary non-lignified walls, which provides mechanical support for growing organs.
2) Parenchyma, collenchyma, Sclerenchyma are ——- type of tissue.
Ans: Parenchyma, collenchyma, Sclerenchyma are simpletype of tissue.
Explanation: Because, simple tissues are homogeneous tissues composed of structurally and functionally similar cells like parenchyma, collenchyma and sclerenchyma.
3) —— and —– are complex tissues.
Ans: Xylem and phloemare complex tissues.
Explanation: Because, complex tissues are made of more than one type of cells which work together as a unit and common examples of complex tissues are xylem and phloem.
4.) Epithelial cells with cilia are found in —— of our body.
Ans: Epithelial cells with cilia are found intrachea of wind pipeof our body.
Explanation: Because, the function of ciliated epithelium is to move particles or mucus in a specific direction over the epithelium.
5) Lining of small intestine is made up of
Ans: Lining of small intestine is made up of columnar epithelium.
Explanation: Because, they are mainly involved in the secretion and absorption.
State whether true or false. If false, correct the statement.
(1) Epithelial tissue is protective tissue in animal body.
Ans: True
Because, epithelial tissues composed of one or more layers of cells covering the external surface of the body and internal organs.
(2) Bone and cartilage are two types of areolar connective tissues.
Ans: False
Correct statement: Bone and cartilage are two types of supportive or skeletal connective tissues.
(3) Parenchyma is a simple tissue.
Ans: True
Because, parenchyma are simple permanent tissues composed of living cells.
(4) Phloem is made up of tracheids.
Ans: False
Correct statement: Phloem is made up of sieve elements, companion cells, phloem fibers and phloem parenchyma.
(5) Vessels are found in collenchyma.
Ans: False
Correct statement: Vessels are found in xylem.
Because, xylem is the conducting tissue which conducts water, mineral nutrients upward from root to leaves.
Answer briefly.
(1) What are intercalary meristems? How do they differ from other meristems?
Ans:
- Meristem is the word derived from Greek word Meristos which means divisible or having cell division activity.
- Meristematic tissues are the group of immature cells which are having capacity to undergo cell division. Meristem is found in plants in those zones only where growth can takes place.
- For example: apex of stem, root, leaf primordia, etc.
- These are the living cells, which are small, oval, and polygonal or round in shape.
- They undergo mitotic cell division and do not store food materials.
- There are three types of meristems in plants based on their position.
- Apical meristem, intercalary meristem and lateral meristem.
Intercalary meristem:
- These cells lies between the region of permanent tissues and which is the part of primary meristem.
- It is found at the base of leaf e.g. pinus or at the base of internodes e.g. grasses.
- These meristem differs from other by their position such as they are located at the base of grass leaves.
(2.) What is complex tissue? Name the various kinds of complex tissues.
Ans:
- Complex tissues are made from more than one type of cells that are working together as a unique.
- These complex tissues consist of parenchyma and sclerenchyma cells.
- Xylem and phloem are the two kinds of complex tissues.
- Xylem is a conducting tissue which conducts water, minerals and nutrients to upper parts of plants from root to leaves by giving mechanical support to the plant body.
- It is made up of xylem tracheids, xylem fibers, xylem vessels and xylem parenchyma.
- Phloem:
- Phloem is a complex tissue which consists of sieve elements, companion cells, phloem fibers and phloem parenchyma.
(3.) Mention the most abundant muscular tissue found in our body. State its function.
Ans:
The most abundant and widely distributed tissues in our body are connective tissues. It provides structural frame work and support and supports to different tissues forming organs.
The components of connective tissues are the intercellular substance called as matrix, connective tissue cells and fibers.
The function of connective tissue is to prevent the organs from getting displaced by the body movements.
The connective tissues are classified as connective tissue proper, supportive connective tissue, dense connective tissue and fluid connective tissue.
(4.) What is skeletal connective tissue? How is it helpful in the functioning of our body?
Ans:
The supportive connective tissue which are also called as skeletal connective tissues forms the endoskeleton of the vertebral body and protects from the various organs and also helps in locomotion.
This supportive tissue includes the cartilage and bone.
Cartilage are soft, semi-rigid and less vascular in nature.
Cartilage is present at the tip of the nose, external ear, end of long bones, trachea and larynx. Cartilage provides the support and flexibility to the body parts.
Bone: Bone is the solid, strong and non-flexible skeletal connective tissue. Its matrix is rich in calcium salts and collagen fibers which provides strength to the bone.
It provides structural frame work and shape to the body. Bones support and protect to soft tissues and organs.
(5) Why should gametes be produced by meiosis during sexual reproduction?
Ans:
Because meiosis is the type of cell division which produces sex cells or gametes.
In meiosis chromosome number is reduced from diploid to haploid due to which it is also called as reduction division.
It produces four daughter cells from one parent cell.
Meiosis occurs only in reproductive cells which involves in gamete formation only during the reproductively active age.
(6) In which stage of mitosis the chromosomes align in an equatorial plate? How?
Ans:
In this type of cell division one parent cell divided into two daughter cells, each having nucleus with the same amount of DNA, same number of chromosomes and genes as the parent cells and hence mitosis is also called as equational division.
In the metaphase of mitosis the chromosomes align in an equatorial plane.
The duplicated chromosomes arrange on the equatorial plane and forms the metaphase plate.
In this way, each chromosome gets attached to a spindle fiber with the help of centromere.
And centromere of each chromosome get divided into two with each being associated to a chromatid.
In this way, in metaphase of mitosis the chromosomes get aligned in an equatorial plate.
Answer in detail.
(1) What are permanent tissues? Describe the different types of simple permanent tissues.
Ans:
Permanent tissues are the tissues in which growth is stopped either completely or for the short time. Sometimes, they become meristematic partially or wholly. Permanent tissues are of two types, simple tissue and complex tissue.
Simple tissues are homogeneous tissues which are composed of structurally and functionally similar cells like Parenchyma, Collenchyma and Sclerenchyma.
Parenchyma:
Parenchyma are simple permanent tissues which are composed from living cells. They are thin walled, oval, rounded or polygonal in shape with a specific spaces between them. In aquatic plants, parenchyma possesses intercellular air spaces which are called as Aerenchyma.
Parenchyma stores water in most of the succulent and xerophytic plants. It provides the functions of storage of food reserves, absorption, buoyancy, secretion etc.
Collenchyma:
Collenchyma is a living tissue found beneath the epidermis. Cells are elongated with unevenly thickened walls.Cells are having rectangular oblique or tapering ends with persistent protoplast. They possess thick primary non-lignified walls and provides mechanical support for growing organs.
Sclerenchyma:
Sclerenchyma made up of thick walled cells which are often lignified. Sclerenchyma cells are dead and do not possess living protoplasts at maturity. Sclerenchyma cells are grouped into fibres and sclereids.
Fibres are elongatedsclerenchymatous cells and mainly with pointed ends. Their walls are lignified. Fibres are abundantly found in plants.
Sclereids are mostly distributed in wide range in plant body. They are mainly broad and occur in single or in groups. Sclereids are isodiametric, with liginified walls.
(2) Write about the elements of Xylem.
Ans:
Complex tissues are made up of more than one type of cells that work together as a unit. Common examples are xylem and phloem.
Xylem is one type of conducting tissue which conducts water, minerals and nutrients to the upper parts from root to leaves. It gives the mechanical support to the body of plant. The elements of xylem are xylem tracheids, xylem fibers, xylem vessels and xylem parenchyma.
i) Xylem tracheids:
These are the elongated tube like dead cells with hard, thick and lignified walls. Their ends are tapering, blunt and devoid of protoplast and with large lumen without any content. The main work of xylem tracheids is to conduct water and provides support to plant body.
ii) Xylem fibers:
They are elongated, lignified and pointed at the both ends. They also provide mechanical support to plant body.
iii) Xylem vessels:
These are the long, cylindrical, tube like structures with lignified walls and presence of wide central lumen. Due to the absence of protoplast these cells are the dead cells. Their main function is to transport water to give mechanical strength to the plant body.
iv) Xylem parenchyma:
These are the living and thin walled cells. The main function of xylem parenchyma is to store starch and fatty substances.
(3) List out the differences between mitosis and meiosis.
Ans:
1) In mitosis, one parent cell get divided into two identical daughter cells each having the nucleus with same amount of DNA, same number of chromosomes and genes as a parent cell.
In meiosis, the sex cells or gametes are produced and the chromosome number is reduced from diploid to haploid and hence it is also called as reduction division.
It produces four daughter cells from one parent cell.
2) Mitosis occurs in two events that are karyokinesis and cytokinesis.
Whereas meiosis occurs in two divisions that are heterotypic division and homotypic division.
3) Mitosis occurs in somatic cells while meiosis occurs in reproductive cells only.
4.) Mitosis involves growth and occurs continuously throughout the whole life. Whereas meiosis involves the gamete formation only during reproductively active age.
5.) Mitosis consist of single division and two diploid daughter cells are formed.
Whereas meiosis consist of two divisions and four haploid daughter cells are formed.
1) In mitosis, the chromosome number of daughter cell is same as the parent cell.
While in meiosis, the chromosome number of daughter cell is half of the chromosome number of parent cell.
2) Daughter cells are identical to parent cell in mitosis.
And not identical to parent cell in meiosis.
VII. Higher Order Thinking Skills.
(1) What is the consequence that occur if all blood platelets are removed from the blood?
Ans:
If blood platelets are removed from the blood, then there will be no blood clotting.Because, they are minute, anucleated, fragile fragments of giant bone marrow called as mega karyocytes and plays important role in blood clotting mechanism.
If there are no platelets, then after injury to our body, there will be continuous flow of blood up to a long time and thereby weaknesses in the body.
Hence, platelets in the blood plays most important role in the blood clotting mechanism.
(2) Which are not true cells in the blood? Why?
Ans:
True cells are those cells which are having nucleus.
But in blood, platelets are the only cells which are not having nucleus that is they are anucleated.
Hence, they are not the true cells.
