Grade 9 - Cells and Tissue

(F) Who discovered the cell

Robert Hooke

(F) Who discovered first living cell

Antonie van Leeuwenhoek

(F) Ho coined term protoplasm

Purkinje

(F) Who discovered the nucleas

Robert Brown

(F) Who worked on the cell theory

Theodor Schwann , Matthias Schleiden , Rudolf Virchow

(SA) Plasma Membrane

1. It acts as an outer covering of the cell

2. It consists of a selectively permeable membrane

3. Osmosis takes place through the plasma membrane

(D) Osmosis

The movement of solvent (water) molecules through a semipermeable membrane from an area of it’s higher concentration to it’s lower concentration.

(LA) Explain the different types of solutions

Isotonic Solution

1. The concentration of solute and water is equal in the medium and inside the cell

2. There is no net movement of water.

3. The size of the cell stays the same

Hypertonic Solution

1. The concentration of water (solvent) is lower in the medium than inside the cell.

2. There is a movement of water outside the cell. This is called endosmosis

3. The cell will shrink

Hypotonic Solutions

1. The concentration of water (solvent) is higher in the medium surrounding the cell than inside the cell

2. There is a movement of water inside the cell. This is called endosmosis.

3. The cell will swell up.

(SA) Cell wall

1. Cell wall is a covering in addition to plasma membrane present in plant cells.

2. It is made up of cellulose

3. It allows the plant to witsand hypotnic solutions

4. When put in a hypotonic solution due to osmosis the contents of the cell shrink away from the cell wall. This is known as plasmolysis

(F) What solutions can be used to stain the cell.

Iodine solutions , safranin solution , methylene blue

(LA) Nucleus

1. The nucleus is a double membrane bound spherical structure that contains genetic material

2. It is covered by a double layered membrane known as nuclear membrane

3. The membrane contains nuclear pores which allow the transfer of materials between cytoplasm and nucleus

4. The nucleus contain chromosomes which are used for cell reproduction

5. Chromosomes are formed from chromatin material when the cell is ready for reproduction

6. Chromosomes are made of DNA and Protein

7. DNA stands for deoxyribonucleic acid. It stores the genetic information necessary for the construction and organisation of a cell.

8. The functional segments of DNA are called genes

9. Prokaryotes lack a membrane bound nucleus they consist of nucleoid

10. In prokaryotes chlorophyll is not stored in plastids but membraneous vesicles

(D) Cytoplasm

Cytoplasm is the fluid content enclosed within the plasma membrane

(LA) Differentiate between prokaryotes and eukaryotes

Prokaryotic Cell

1. They are very small is size ranging from 1 - 10 micrometers

2. They do not have a membrane bound nucleus but only a region containing nucleic acid known as nucleoid

3. They only have one chromosome

4. Membrane bound cell organelles are absent

Eukaryotic Cell

1. They are larger in size ranging from 5 - 100 micrometers

2. They have a double membrane bound nucleus

3. They contain multiple chromosmes

4. Membrane bound cell organelles are present

(LA) Endoplasmic Reticulum

1. The endoplasmic reticulum is a network of membrane bound vesicles.

2. There are two types of ER , Smooth Endoplasmic Reticulum and Rough Endoplasmic Reticulum

3. RER appears rough as they contain ribosomes and synthesise proteins

4. SER synthesise lipids and fats

5. These proteins , lipids and fats sometimes act as regulating hormones

6. SER plays a crucial role in detoxifying many poisons and drugs

7. The ER acts as a medium of transport of substances mainly proteins through the cell

8. The ER form the cytoplasmic framework which act as a surface for biochemical activities of the cell

9. Some of the proteins and lipid molecules synthsized help build the cell membrane in a process known as membrane biogenesis

(LA) Golgi Appartus

1. The Golgi apparatus consists of membrane bound vesicles that form sacs called cisterns

2. They package and transport the materials synthesised in the ER to various targets inside and outside the cell.

3. The functions of the Golgi Complex include storage , transportation and packaging of materials

4. It was discovered by Camilio Golgi

5. It produces lysosomes.

(SA) Lysosomes

1. Lysosomes are membrane bound organelles that contain digestive enzymes produced by the ER.

2. They help clean up the cell by breaking down waste materials and worn out organelles

3. They also break down foreign particles such as bacteria that enter the cell.

4. In certain conditions , such as if a cell is damaged the lysosomes release their enzymes digesting the cell itself

(SA) Mitochondria

1. Mitochondria is a double membranous organelle that produces energy for the cell in the form of Adenosine Triphosphate.

2. ATP is used to create new chemical compounds and perform mechanical work

3. The outer covering of mitochondria is porous while the inner covering of mitochondria is deeply folded to increase the surface area for ATP production

4. They have their own dna which allows them to be semi autonomous , manufacture their own proteins and duplicate themselves in times of need,

(LA) Plastids

1. Chromoplasts - pigment containing plastids

2. Leucoplasts - transparent plastids that store starch , sugars etc.

3. Chloroplats - plastids that contains chlorphyll

Properties of Plastids

1. They have a double membrane

2. They have their own DNA and ribosomes

3. They consist of membrane layers embedded in a material called stroma

(SA) Vacuoles

1. They are storage sacs in the cell

2. They are alrger in plant cells than animal cells

3. THey contain cell sap and providde turgidity and rigidity to the pcell

4. It stores many important substances like amino acids , sugars and organic acids , proteins.

5. In some unicellular organisms the vacuoles help in expelling excess water and some wastes from the cell

(SA) Meristematic Tissue

1. Meristematic tissue are the tissues that divide and help grow the plant

2. They have a dense cytoplasm , large nucleus , thin wall

3. Vacuoles are absent

(SA) Types of Meristematic Tissue

1. Apical Meristem - present on the growing tips of plants and helps increase the height

2. Lateral Meristem - present on the lateral side of stem and it helps increase it’s thickness and girth

3. Intercalary Meristem - It is presentt near the node and help grow new leaves , stem and buds

(LA) Differentiate between animal and plant tissue

Plant Tissue

1. They are designed to be stationary

2. Consist of living and non living cells

3. Use less energy

4. Have unlimited growth

5. Undergo differentiation

Animal Tissue

1. They are designed for movement

2. Consist of only living cells

3. Uses more energy

4. Have limited growth

5. Do not undergo differentiatiion

(D) Differentiation

The process in which meristematic tissues stop dividing and take up a specific role or function.

(LA) Simple Meristematic Tissue and it’s types

(D) Cutin , Lignin , Suberin

1. Lignin is present in the sclerenchyma and given it it’s hardness

2. Cutin is the waxy coating on the epidermis in some plants to prevent the water loss

3. Suberin is present in the cork cell and makes it impervious to gas and water

(LA) Epidermis Functions

(LA) Differentiate between xylem and phloem

(SA) Xylem and it’s parts

1. Tracheids - they are dead cells with pits and they help in the vertical movement of water

2. Xylem Vessels - they are dead cells with pits that help in the conduction and movement of water

3. Xylem parenchyma - only living cells of xylem , it stores food for the tissue and helps in sideways conduction of water

4. Xylem Fibres - also dead cells that the xylem in its functions. They are not perforated

(SA) Phloem and it’s parts

1. Sieve tubes - tubular cells with perforated walls

2. Sieve cells - sieve cells do not form into sieve tubes and lack sieve plates

3. Companion cells - small elongated cells that help in the translocation of food

4. Phloem fibres - the only dead cells which are made of sclerenchyma

5. Phloem parenchyma - stores food for the phloem and helps in lateral conduction

(SA) Differentiate between meristematic tissue and permanent tissue

Meristematic Tissue

1. Cells divide rapidly

2. Vacuoles are absent

3. Always living cells

4. Its types are apical . lateral and intercalary

Permanenet Tissue

1. Cells do not divide as they have undergone differentiation

2. Vacuoles are present

3. Can be living or dead

4. Mention its types

(F) What is collagen

substnace present in the basement membrane of epithelium

(SA) Epithelial Tissue

1. It form a barrier to keep different body parts seprated

2. It covers most organs and cavitiies of the bodu

   1. The basement membrane containg collagen seprates the epitehlium from the underlying tissues

(LA) Types of Epithelium

1. Squamous Epithelium - single layered flat cells that cover the linings of blood vessels and alveoli where substance transport occurs

2. Stratified squamous - found in the skin , it is a squamous epithelium with cells aranged in many layers to prevent wear and tear

3. Cuboidal - manily provides mechanical support , also performs functions of absorbtion and secretion found mostly in salivary glands and kidney tubules

4. Columnar - tall pillar like cells usually found in the inner lining of the small intestine that perform the functions of absorbtio and secretion

5. Ciliated Columnar - they have cilia which help in pushing or moving substances like mucus forward. It is found in the repiratory tract , spermducts and oviducts

6. Glandular epithelium - when epithelial tissue folds inwards to form a multicellular gland it is called a glandular epithelium

(F) what minerals are present in bone

calcium and phosphorous

(SA) Charecteristics of connective tissue

The cells are loosly spaced and embedded in an intercellular matrix which may be solid or liquid

(SA) DIfferentiate between tendons and ligament

Ligament

1. Joins bone to bone

2. Elastic and flexible

3. Made of yellow fibrous tissue

Tendon

1. Joins muscle to bone

2. Rigid and tough

3. Mad of white fibrous tissue

(SA) Differentiate between areolar and adipose tissue

(SA) Differentiate between striated , non striated and cardiac muslce tissue

Striated

1. Multinucleated

2. Cylindrical in shape

3. Present in limbs , face , neck etc.

4. Unbranched fibres

5. Voluntary in action

Unstriated

1. Uninucleated

2. Spindle Shaped

3. Present in iris , alveoli , uterus etc.

4. Unbranched fibres

5. involuntary in action

Cardiac

1. Uninucleated

2. Cylindrical

3. Present in heart

4. branched fibres

5. involuntary in action

(SA) Nerve tissue

The nerve tissue carries electrical signals throught the body from the brain.It’s structure consists of

1. Dendrites which receive signals from other neurons and allow transmission

2. Cell body - contains all the normal things like nucleus , golgi body etc.

3. Axon - the tube like long structure that carries the impulse

4. Synapse - it is the chemical junction between the terminal of one neuron and the dendrite of another neuron