Test: The Fundamental Unit of Life - 2 - UPSC

Water molecules will move from a region of higher concentration to a region of lower concentration. Thus, if the cells are placed in a solution where the concentration of water is more outside, the cell will absorb water. It will help in imbibition of the cell and thus, cell will swell up.

When the plant cell is placed in a hypotonic solution , it takes up water by osmosis and starts to swell, but the cell wall prevents it from bursting.

Prokaryotes are organisms without a distinct cell nucleus or any other membrane-bound organelles. Most are unicellular, but some prokaryotes are multicellular.

The ribosome is found in prokaryotic cell and it functions in the translation of messenger RNA into proteins.

Prokaryotes and eukaryotes are the two different type of cell. The structure of cell differentiate the prokaryotic and eukaryotic cells. Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not but the ribosome is the only organelle that can be seen in both cells prokaryotic and eukaryotic.

Both mitochondria and plastids possess  their  own genetic material and ribosomes .

The mitochondria DNA and plastid DNA possess genes which produce the proteins necessary for the functioning  of mitochondria and plastids  respectively. 

• The endoplasmic reticulum is of two types on the basis of the presence of ribosomes.
  i) If the endoplasmic reticulum ribosomes are attached to them then it is called a rough endoplasmic reticulum and
  ii) If there are no ribosomes on the endoplasmic reticulum then it is called a smooth endoplasmic reticulum.
• Rough endoplasmic reticulum produces and transports protein and smooth endoplasmic reticulum produces and transports lipids which provide a framework to the plasma membrane by a known as membrane biogenesis.

Organisms like Amoeba have flexible cell membrane due to which they can take in food material or engulf foreign bodies through the process called endocytosis.

• Vacuoles are storage bubbles found mostly in plant cells. These are used for storage of food or water. 
• The vacuolar membrane is a single layered and is called as tonoplast. 
• Osmotic pressure and turgidity is maintained by vacuoles. 
• They store toxic metabolic by-products or end products of plant cells. Such vacuoles are thrown out of the cell by exocytosis.
• Thus, the correct answer is Locomotion is not a function.

Prokaryotes are unicellular primitive organisms that possess nucleus without the nuclear membrane.

They do not possess membrane-bound cell organelles. As they are unicellular organism they lack division of labor.

Smooth endoplasmic reticulum in liver cells of vertebrates helps in detoxification.

It metabolises various toxic or poisonous substances such as drugs, aspirin, insecticides (DDT), petroleum products and pollutants.

These toxic substances make their entry in animal's body through food, air or water.

The Golgi apparatus receives proteins and lipids (fats) from the rough endoplasmic reticulum.

It modifies some of them and sorts, concentrates and packs them into sealed droplets called vesicles.

Option B: Rough endoplasmic reticulum produce proteins and smooth endoplasmic reticulum produce lipids. Hence, given statement is wrong. 

Option C: Endoplasmic reticulum is related with the making of plasma membrane. It makes the proteins (with the help of ribosomes) and lipids which are used for membrane synthesis. Hence, given statement is false.

Option D: Nuclear material of a prokaryotic cell consists of a single chromosome which is not membrane bound and lies naked in cytoplasm. Such, nuclear region of cytoplasm is called as nucleoid. Hence, given statement is wrong.

Option A: Lysosomal enzymes are made by rough endoplasmic reticulum. The ribosomes present on rough endoplasmic reticulum are involved in protein synthesis. Almost all enzymes are proteins

So, the correct answer is 'Enzymes packed in lysosomes are made through RER (rough endoplasmic reticulum)'

• The endoplasmic reticulum (smooth and rough) is an interconnected network of flattened, membrane-enclosed sacs or tube-like structure which are evenly distributed throughout the cytoplasm.
• Smooth endoplasmic is not studded with ribosomes.
• The smooth endoplasmic reticulum contains enzymes which catalyze a series of reactions that detoxifies lipid-soluble drugs and other harmful metabolic substances produced.

So, the correct answer is 'SER'.

• The chloroplast is a type of plastid which produces green coloured pigment. The chloroplast is involved in carrying out photosynthesis. It gives a green colour to leaves. 
• Chromoplasts are a type of plastids which are responsible for the characteristic colour of flower and fruit. They are involved in attracting insects, various vectors for pollination and for fruit dispersal.
• Leucoplasts are colourless plastids and mainly help in storage of food compounds like starch, proteins or fats. Such colourless plastids are present in underground roots, stems.

Rudolf Virchow famously stated "Omnis cellula e cellula", i.e., "All cells only arise from pre-existing cells." Virchow was a major advocate of the cell theory and published an influential theory that cells arose from each other in a continuous series of generations.

Osmosis is the passive movement of water or any other solvent molecules from a region of higher water concentration to a region of lower water concentration through a semipermeable membrane. This brings both the solutions separated by the semipermeable membrane to the equilibrium. Therefore, option A is correct. 

The mature cell has simple tissues rather than meristematic tissues so they will not divide and plant cell needs vacuole to make itself rigid and various excretion and storage works are also done by the vacuoles.

So, the vacuoles perform majority of the tasks of the plant cell and hence this is the reason, a mature plant cell has 70-80% of vacuoles in them.

Chromosomes are made of DNA-histone protein complexes.

Chromosomal DNA is packaged inside nuclei with the help of histones. These are positively charged proteins that strongly adhere to negatively charged DNA and form complexes called nucleosomes.

Each nucleosome is composed of DNA wound 1.65 times around eight histone proteins.

Cell sap is the fluid present in the vacuole. The contents of cell sap are salt, sugar and water. Water is predominantly found in cell sap.

Robert Hooke, a scientist, was the first person to discover the existence of cells with the help of a microscope in 1665 but they were dead cells.

Anton van Leeuwenhoek, in 1674 with the improved microscope, discovered free-living cells of algae Spirogyra in pond water for the first time.

Most of the substances in the living world are transported across the cell membrane by the process of osmosis.