Cell : structure and functions

Q1) The genetic information of an organism is presented in the ………Chromosomes ………….

Q2) Deoxyribonucleic acid ( DNA ) in plants and animals cell is presented in the ………….. nucleus ……….

Q3) Cellular respiration occurs in cell organelles called ………… mitochondria …………….

Q4) one of the difference between a plant and an animal cell is the presence of…….chloroplasts……….

Q5) The organelle that accumulates excess water and removes it from the cell is called …….contractile vacuole …….

Q6) The cell wall in a plant cell is mainly made up of …….. cellulose…….

Q7) the centriole helps in moving chromosomes during ………cell division…….

Q8) chloroplasts in a plant cell contain…..chlorophyll…..

-Write True or False

   1)   Multicellular animals have one cell.                

( False )

   2)  The basic living unit of an organism is a cell.

( True)

   3)  Paramecium and euglena are multicellular animals.

( False )

   4) The nucleus contains chromosomes.

( True )

   5)  Lysosomes are called the power house of the cell .

( False )

-Answer the following:

Q1) Which organelle of the plant cell has chlorophyll ?

Ans:

Chloroplasts.

Q2) which cells have a cell wall ?

Ans:

Plant cell

Q3) what is the cell wall made up of.

Ans:

Cellulose

Q4) what is the function of the endoplasmic reticulum ?

Ans:

Production of protein and lipid components in the cell.

Q5) what is epidermis?

Ans:

The outermost layer of the root, stem, leaf or fruit is the epidermis.

Q6) Explain the function of the nuclear membrane?

Ans:

The nucleus controls the activities of the cell. It is bounded by a membrane called the nuclear membrane. This membrane is porous and allows movement of materials in and out of the nucleus.

Q7) Why are stains and dyes used to observe cells?

Ans:

Cells are transparent and colourless. They are therefore difficult to be observed under microscopes. That is why stains and dyes of different colours are used rto observe cells and their fine structure. Some common stains are safranin, eosin and methylene blue. These stains react with specific parts of the cells and make them clearly visible under a microscope.

Q8) The cell is the basic structural unit of every living organism. Explain?

Ans:

The structural unit of all living organisms is a cell. This means that every living organism like bacteria.

Amoeba, paramecium and euglena are made up of a single cell. Such organisms are called unicellular organisms.

Other living organisms begin their life as a single cell. A single fertilized egg cell multiplies into millions of cells to form a new organism such organisms are called multicellular organisms.

Q9) differentiate between eukaryotes and prokaryotes?

Ans:

In certain organisms such as bacteria and blue –green algae, the nucleus is not well organized and not bounded by a nuclear membrane. Such organisms are called prokaryotes.

All other organisms in which the nucleus is well organized with a nuclear membrane are called eukaryotes.

Q10) What are the functions of endoplasmic reticulum?

Ans:

There are two types of endoplasmic reticulum. The rough and the smooth endoplasmic reticulum. The endoplasmic reticulum is responsible for production of protein and lipid components in the cell. They also help in the transport of proteins.

Q11) how is flagella different from cilia? What are their functions?

Ans:

Many cells have hair like structures projecting from their surface called flagella or cilia. Flagella are long and few in number while cilia are short and numerous.

Q12) what are genes?

Ans:

Chromosomes carry genes, the units of inheritance which means that they transfer characteristics from parents to off siblings.  

Q13) Where are chromosomes found in cell? State their function.

Ans:

Chromosomes are made up of deoxy ribonucleic acid (DNA). Chromosomes carry genes, the units of inheritance which means that they transfer characteristics from parents to off siblings.

Q14) explain that a cell is the functional unit of living organisms.

Ans:

The cell is the functional unit of a living organism, this means that a living organism carries out most of its functions in its cells.

For example: the enzymes that digest food are produced by the cells of the digestive glands. Blood transports oxygen and carbon dioxide. These gases bind to the red blood cells and are transported to all parts of the body.

Q15) Describe the nucleus of a cell.

Ans:

The nucleus controls the activities of the cell. It is bounded by a membrane called nuclear membrane.

This membrane is porous and allows movement of materials in and out of the nucleus. The fluid inside the nucleus is called the nucleoplasm. Suspended in the nucleoplasm is a spherical body called the nucleolus. The nucleus also contains a number of thread like bodies called chromosomes.

Q16) Draw and label plant cell and animal cell

Q 17)

Indicate whether the following statements are True (T) or False (F).

(a) Unicellular organisms have one-celled body. (T)

(b) Muscle cells are branched. (F)

(c) The basic living unit of an organism is an organ. (F)

(d) Amoeba has irregular shape. (T)

Q18)

Make a sketch of the human nerve cell. What function do nerve cells perform?

Ans:

The function of a nerve cell is to transmit messages to the brain and also to take away messages from the brain to the receptor organs. Thus, it controls the working of different parts of the body.

Q19) Write short notes on the following.

(a) Cytoplasm

(b) Nucleus of a cell

(c) Nuclear membrane

(d) Nucleolus

(e) Chromosomes

Ans:

(a) Cytoplasm:

It is a fluid that fills the cell and occurs between the plasma membrane and the nucleus. Cell organelles such as mitochondria, ribosomes, Golgi bodies, etc. are suspended in the cytoplasm. The cytoplasm helps in the exchange of materials between cell organelles.

(b) Nucleus of a cell:

The nucleus is a spherical structure generally present at the centre of a cell. The nucleus is composed of the following components:

(c) Nuclear membrane:

It is a double-layered membrane which separates the contents of the nucleus from the cytoplasm. The nuclear membrane has nuclear pores that allow the transfer of specific substances in and out of the nucleus.

(d) Nucleolus:

It is a small spherical body that is not bound by any membrane.

(e) Chromosomes:

These are thread-like structures that carry genes. Genes contain information necessary for the transfer of characteristics from the parents to the offspring. Thus, chromosomes play an important role in the inheritance of characteristics.

Q20)Which part of the cell contains organelles?

Ans:

Cytoplasm is the part of the cell that contains various organelles such as mitochondria, ribosomes, Golgi bodies, etc. Cytoplasm is a fluid that fills the cell and occurs between the plasma membrane and the nucleus.

Q21) Make sketches of animal and plant cells. State three differences between them.

Ans:

Q22) State the difference between eukaryotes and prokaryotes.

Ans:

Q23)Where are chromosomes found in a cell? State their function.

Ans:

The nucleus contains thread-like structures called chromosomes. Chromosomes play an important role in the inheritance of characters. They carry genes that help in the transfer of characters from the parents to the offspring.

Q24)'Cells are the basic structural units of living organisms’. Explain.

Ans:

Cells constitute various components of plants and animals. A cell is the smallest unit of life and is capable of all living functions. Cells are the building blocks of life. This is the reason why cells are referred to as ‘the basic structural and functional units of life’. All cells vary in their shapes, sizes, and activities they perform. In fact, the shape and size of the cell is related to the specific function it performs.

Q25) Explain why chloroplasts are found only in plant cells?

Ans:

Chloroplasts are found only in plant cells. They contain a green pigment called chlorophyll. This green pigment is important for photosynthesis in green plants. This chlorophyll pigment traps solar energy and utilizes it to manufacture food for the plant.

Q26) Complete the crossword with the help of clues given below.

Q27) Complete the crossword with the help of clues given below.

Across

1. This is necessary for photosynthesis.

3. Term for component present in the cytoplasm.

6. The living substance in the cell.

8. Units of inheritance present on the chromosomes.

Down

1. Green plastids.

2. Formed by collection of tissues.

4. It separates the contents of the cell from the surrounding medium.

5. Empty structure in the cytoplasm.

7. A group of cells.

Ans:

Across

1. CHLOROPHYLL

3. ORGANELLE

6. PROTOPLASM

8. GENES

Down

1. CHLOROPLASTS

2. ORGAN

4. MEMBRANE

5. VACUOLE

7. TISSUE