Cell Structure And Function NCERT Solutions for Class 8

Cell Structure and Function Class 8 is an essential unit prescribed focusing on the basic unit of life, the cell, its structure and different types of functions it performs. The chapter aids in developing a stronger base of Cell Structure And Function Class 8 in students’ minds, so they can do well in their exams. These solutions provide in-depth knowledge of the concepts, therefore, learners can use them to prepare their notes.

NCERT Solutions For Class 8 Science Cell Structure And Function

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

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

(b) Muscle cells are branched. (T/F)

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

(d) Amoeba has irregular shape. (T/F)

Soln:

a)True

b) False

c) False

d) True

Q2. Make a sketch of a human nerve cell. What function do nerve cells perform? \section*

{Solution} \textbf{Structure of the Neuron:} \begin{center} \includegraphics[width=0.5\textwidth]{neuron.jpg} % Replace with the path to your image \end{center} \textbf{Description:} The nervous system is made up of specialized cells called neurons. Neurons are the structural and functional elements that help in the coordination of body activities. They are specialized to conduct and respond to stimuli by transmitting nerve impulses. Neurons have three distinct parts: 1. **Cell Body (Soma):** Each neuron has a cell body that contains a nucleus, Golgi apparatus, endoplasmic reticulum, mitochondria, and other organelles. The cell body receives electrical impulses from the dendrites. 2. **Dendrites:** These are branch-like structures that receive messages from other neurons and transmit them to the cell body. Dendrites allow the transmission of messages to the cell body by receiving electrical impulses from the axonal ends of other neurons. 3. **Axon:** The axon is a tube-like structure that carries electrical impulses from the cell body to the axon terminals. It is the longest single extension of the neuron and transmits nerve impulses via nerve endings. \textbf{Synapse:} Synapses are the nerve endings of neurons where neural impulses are transmitted between neurons. They consist of three main components: – A pre-synaptic ending – A synaptic cleft – A post-synaptic ending The neurotransmitters produced in the neuron cross the synaptic cleft and bind to receptors in the postsynaptic ending, stimulating an action potential in the postsynaptic neuron. Neurons play a crucial role in receiving, processing, and transmitting information throughout the body, enabling sensory perception, motor function, and cognitive abilities.

3. Write short notes on the following. (a) Cytoplasm (b) Nucleus of a cell \section*

{Solution} \textbf{(a) Cytoplasm:} The cytoplasm is a fluid that fills the cell and is located between the plasma membrane and the nucleus. It contains cell organelles such as mitochondria, ribosomes, Golgi bodies, etc., which are suspended in the cytoplasmic matrix. The cytoplasm plays a crucial role in the exchange of materials between cell organelles and supports various cellular processes. \vspace{0.5cm} \textbf{(b) Nucleus of a cell:} The nucleus is a spherical structure generally located at the center of a cell. It serves as the control center of the cell and contains the genetic material. The nucleus is composed of the following components: \begin{itemize} \item \textbf{Nuclear membrane:} This is a double-layered membrane that separates the contents of the nucleus from the cytoplasm. The nuclear membrane is perforated with nuclear pores, which allow the transfer of specific substances in and out of the nucleus. \item \textbf{Nucleolus:} The nucleolus is a small, spherical body within the nucleus that is not bound by any membrane. It is primarily involved in the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomes. \item \textbf{Chromosomes:} Chromosomes are thread-like structures made of DNA and proteins. They carry genes, which contain the information necessary for the inheritance of characteristics from parents to offspring. Thus, chromosomes play an essential role in the transmission of genetic information and the regulation of cellular activities. \end{itemize}

4. Which part of the cell contains organelles?

Soln:

Various cell organelles are present in the cytoplasm. It is a clear and colourless fluid that contains organelles like Mitochondria, Ribosomes, and Golgi Bodies.

5. Make sketches of animal and plant cells. State three differences between them. \section*

{Solution} \textbf{Animal Cell:} \begin{center} \includegraphics[width=0.4\textwidth]{animal_cell.jpg} % Replace with the path to your image of an animal cell \end{center} \textbf{Plant Cell:} \begin{center} \includegraphics[width=0.4\textwidth]{plant_cell.jpg} % Replace with the path to your image of a plant cell \end{center} \textbf{Differences between Animal and Plant Cells:} 1. **Size:** – Animal cells are generally smaller in size. – Plant cells are usually larger than animal cells. 2. **Cell Wall:** – Animal cells do not have a cell wall. – Plant cells have a rigid cell wall made up of cellulose, which provides structural support. 3. **Organelles:** – Animal cells have small, multiple vacuoles. – Plant cells typically have a large central vacuole that stores water and maintains turgor pressure. – Plastids (including chloroplasts) are present in plant cells, which are involved in photosynthesis and other functions, but are absent in animal cells.

6. State the difference between eukaryotes and prokaryotes.