First Chapter : Cell and its Structure
সুপ্রিয় ২০২৪ সালের ইংলিশ ভার্সনের এইচএসসি পরীক্ষার্থী বন্ধুরা, শুভেচ্ছা নিও। আজ তোমাদের Biology first paper (Botany)-এর ‘First Chapter : Cell and its Structure’ থেকে আরও ১টি CQ প্রশ্ন ও উত্তর নিয়ে আলোচনা করা হলো।
2. Read the text and answer the questions below.
Plant cell has many cell organelles, among these one cell organelle is involved with energy production another organelle is related to food production.
a. What is Labilizer?
Ans: Some substances that help to break down the membrane of the lysosome so that the enzyme perform the autolysis. These substances are called labilizar.
b. Why the lysosome is called suicidal bag?
Ans: During the acute food crisis, the wall of lysosome burst out and the covered enzymes come out and destroy the other organelles.
This phenomenon is said to be autophagy. In this way the entire cell may undergo digestion. This process is known as autolysis. Since the lysosome destroys the useless cells with this process autolysis they are known as suicidal bag or squad.
c. Discuss about the types of above mentioned last organelle.
Ans: The above mentioned last organelle is Plastid. The type of plastid is discussed below.
Types of plastid: Plastid mainly is of three types, such as-a) Leucoplast b) Chromoplast c) Chloroplast.
a) Leucoplast: They are colourless
Position: Leucoplast is present in the organs, such as - roots, underground stem etc., where sunlight doesn't reach.
Types: Leucoplast is divided into three types on the basis of the nature of the reserve food. Such as-
Amyloplast: Starch type food storing leucoplast is known as amyloplast.
Elaioplast: Lipid type food storing leucoplast is called elaioplast.
Aleuroplast: Protein storing leucoplast is called aleuroplast or proteinoplast.
b) Chromoplast: The coloured plastids (Except green) are said to be chromoplast. They are coloured because of the presence of carotene (Orange-Red) and Xanthophyll (Yellow). The organs that are coloured contain chromoplast, such as-petals of flowers, coloured fruits and seeds.
c) Chloroplast: Green coloured plastids are known as chloroplast. Chloroplast is made with the combination of chlorophyll-a, chlorophyll-b, carotene and xanthophyll. The green pigment named chlorophyll is present here at a huge number and thus they are green in colour. Other colour pigments are also present at a small amount.
Position: It is present in the green parts of the plant especially in leaves.
d. Explain the structure of the above mentioned 1st organelle.
Ans: The above mentioned 1st organelle is Mitochondria. The structure of the mitochondria is given below-
Physical Structure: Mitochondria include the following parts:
Membrane: It remains covered with a bi-layered membrane.The membrane is a lipoprotein bi-layer in nature. Outer membrane is straight and Its main function is to protect the inner elements. As it is permeable it regulates entering and outgoing of different minute molecules and ions. It has some transport protein so it can help in the active transport. It doesn't have any enzymes like ETC, ATP synthases and enzymes for the formation of ATP etc. It is mainly defensive in nature. Distance between the two membranes is 6-8nm
Chambers: The space between two layers is known as outer chamber or inter- chamber while the chamber covered with the membrane having foldings is called inner chamber. Inner chamber remains filled with a jelly like homogenous substance known as matrix.
Cristae: Outer membrane straight while the inner membrane being folded forms finger like structure. These finger-like structures are called cristae. Their number and shape are different according to different cells. These divide the matrix into some incomplete chambers. The space within the cristae is known as intra-crystal space.
Oxisome: Some ultra-fine granular substances remain attached to the inner wall of the inner membrane of mitochondria are called oxisome. It may be stalked or without stalk. A stalked oxisome comprises of head, stalk and base.
ATP synthases and ETC: There are some round substances called ATP Synthases in different places of cristae. ATP synthesis takes place here. Besides, ETC (electron transport chain) are present throughout the cristae.
Circular DNA & Ribosome: Mitochondria have their own round DNA, RNA and Ribosome (70s). It is similar with the characteristic of a prokaryotic cell. They are present in the matrix.
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