16 November Static Quiz 2021 (Science)

Correct Answer : C
Answer Justification :
Justification: Statement 1 and 2: DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
Statement 3: DNA can replicate or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the
old cell.
Statement 4: However, DNA does more than specify the structure and function of living things — it also serves as the primary unit of heredity in organisms of all types. In other words, whenever organisms reproduce, a portion of their DNA is passed along to their offspring. This transmission of all or part of an organism’s DNA helps ensure a certain level of continuity from one generation to the next, while still allowing for slight changes that contribute to the diversity of life.

Correct Answer : C
Answer Justification :
Justification: Stem cell is an undifferentiated cell of a multi-cellular organism which is capable of giving rise to indefinitely more cells of the same type and from which certain other kinds of cell may be formed by the cellular differentiation. They are found in multi-cellular organisms. In mammals, there are two broad types of stem cells: embryonic stem cells and adult stem cells. Both are generally characterized by their potential to differentiate into different cell types. For e.g. Pluripotent stem cells have the ability to differentiate into almost all cell types. In the stem cell treatments new adult cells are introduced into the damaged tissue to treat the disease. Stem cells offer new potentials for treating diseases such as diabetes, and heart disease.

Correct Answer : C
Answer Justification :
Concept: Osmosis is the diffusion of fluid through a semi-permeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal solute concentration on both sides of the membrane.
Justification: Statement 1: Stomata are responsible for plant gas exchange which enables the process of photosynthesis. On every plant leaf there are many guard cells that literally “guard” the stomata. During osmosis, the guard cells swell with water and the pressure triggers the stomata to open. When the stomata open they suck in carbon dioxide from the air which is then used in combination with the water from the roots and the sunlight absorbed in chlorophyll to produce plant energy.
Statement 2: Roots reach out into the soil to establish an avenue for the transport of nutrients and water to the rest of the plant. The roots absorb water through osmosis. If the water concentration outside of the plant roots is greater than that of the water concentration in the roots osmosis occurs.

Correct Answer : B
Answer Justification :
Justification: Statement 1: Saturated fatty acids are found in foods from animal sources such as butter, milk, meat, salmon, and egg yolks, and some plant-derived products such as chocolate and cocoa butter, coconut, palm and palm kernel oils.
Statement 2: Trans fatty acids (TFAs) or Trans fats are the most harmful type of fats which can have much more adverse effects on our body than any other dietary constituent. These fats are largely produced artificially but a small amount also occurs naturally. Thus in our diet, these may be present as Artificial TFAs and/ or Natural TFAs. Artificial TFAs are formed when hydrogen is made to react with the oil to produce fats resembling pure
ghee/butter. In our diet the major sources of artificial TFAs are the partially hydrogenated vegetable oils (PHVO)/vanaspati/ margarine while the natural TFAs are present in meats and dairy products, though in small amounts.
Statement 3: TFAs pose a higher risk of heart disease than saturated fats. While saturated fats raise total cholesterol levels, TFAs not only raise total cholesterol levels but also reduce the good cholesterol (HDL), which helps to protect us against heart disease. Trans fats consumption increases the risk of developing heart disease and stroke. TFA containing oils can be preserved longer, they give the food the desired shape and texture and can
easily substitute ‘Pure ghee’. Learning: WHO has released draft recommendations on limiting the intake of trans fats. These draft recommendations, the first since 2002, are aimed at controlling non-communicable diseases (NCDs), which are responsible for an estimated 39.5 million death (72%) of the 54.7 million deaths worldwide in 2016.
Key recommendations: Saturated fatty acids should not comprise more than 10% of your daily calorie intake.

Correct Answer : A
Answer Justification :
Justification: Ethylene is formed naturally in plants in amounts sufficient to bring about regulatory
effects. Role of ethylene is in:
 Breaking dormancy
 Induce ripening of fruits
 Induce abscission of leaves
 Inhibit elongation and lateral bud growth
Learning: Ripening is the process by which fruits attain their desirable flavour, quality, colour, palatable nature and other textural properties.
Ripening is associated with change in composition i.e. conversion of starch to sugar. On the basis of ripening behavior, fruits are classified as climacteric and non-climacteric fruits. Climacteric: Climacteric fruits are defined as fruits that enter ‘climacteric phase’ after harvest i.e. they continue to ripen. During the ripening process the fruits emit ethylene along with increased rate of respiration. Ripe fruits are soft and delicate and generally cannot withstand rigours of transport and repeated handling. These fruits are harvested hard and green, but fully mature and are ripened near consumption areas. Small dose of ethylene is used to induce ripening process under controlled conditions of temperature and
humidity.