Botany
- Phloem in gymnosperms lacks : Answer: 4. Both sieve tubes and companion cells Key idea: Gymnosperm phloem has sieve cells and albuminous cells. Sieve tubes and companion... 1
- Select the correct group of biocontrol agents. Answer: 2. *Trichoderma*, *Baculovirus*, *Bacillus thuringiensis* Biocontrol agents include Bacillus thuringiensis (bacterium), Trichoderma... 1
- *Thiobacillus* is a group of bacteria helpful in carrying out : Answer: 4. Denitrification Thiobacillus species oxidise sulphur compounds. The key lists Thiobacillus denitrificans, which converts nitrate... 1
- Match the following organisms with the products they produce :(a) *Lactobacillus* (i) Cheese(b) *Saccharomyces cerevisiae* (ii) Curd(c) *Aspergillus niger* (iii) Citric Acid(d) *Acetobacter aceti* (iv) Bread(v) Acetic AcidSelect the correct option. Answer: 2. (a) (ii) (b) (iv) (c) (iii) (d) (v) Lactobacillus makes curd (ii). Saccharomyces cerevisiae is used for bread (iv). Aspergillus n... 1
- Cells in G_0 phase : Answer: 3. suspend the cell cycle Cells that do not divide further leave the active cycle at G₁ and enter the quiescent G₀ stage. They remai... 1
- Which of the following statements regarding mitochondria is incorrect ? Answer: 2. Enzymes of electron transport are embedded in outer membrane. The enzymes of the electron transport chain are in the inner mitoch... 1
- From evolutionary point of view, retention of the female gametophyte with developing young embryo on the parent sporophyte for some time, is first observed in : Answer: 3. Pteridophytes Key idea: Retention of the female gametophyte with the young embryo on the sporophyte appears first in pteridophyte... 1
- Select the correctly written scientific name of Mango which was first described by Carolus Linnaeus : Answer: 2. textitMangifera indica Linn. Key idea: In a scientific name the genus starts with a capital letter, the species with a small lett... 1
- Which of the following protocols did aim for reducing emission of chlorofluorocarbons into the atmosphere ? Answer: 1. Montreal Protocol Key idea: The Montreal Protocol (1987) controls substances that deplete the ozone layer, mainly CFCs. Kyoto Pro... 1
- Which of the following ecological pyramids is generally inverted ? Answer: 4. Pyramid of biomass in a sea Key idea: A pyramid is inverted when producers weigh less than consumers at a given time. In the sea,... 1
- What map unit (Centimorgan) is adopted in the construction of genetic maps ? Answer: 3. A unit of distance between genes on chromosomes, representing 1% cross over. One map unit (centimorgan) is the distance between g... 1
- In Antirrhinum (Snapdragon), a red flower was crossed with a white flower and in F_1 generation, pink flowers were obtained. When pink flowers were selfed, the F_2 generation showed white, red and pink flowers. Choose the incorrect statement from the… Answer: 4. Law of Segregation does not apply in this experiment. Key idea: Flower colour in snapdragon shows incomplete dominance, but segre... 1
- Conversion of glucose to glucose-6-phosphate, the first irreversible reaction of glycolysis, is catalyzed by : Answer: 2. Hexokinase Key idea: Hexokinase phosphorylates glucose using ATP to give glucose-6-phosphate, the first irreversible step. Phosph... 1
- What is the direction of movement of sugars in phloem ? Answer: 4. Bi-directional Phloem moves sugars from a source to a sink. The source and sink can be anywhere, so movement can be upward or dow... 1
- What is the site of perception of photoperiod necessary for induction of flowering in plants ? Answer: 4. Leaves Key idea: Photoperiod is sensed by the leaves. Leaves perceive the light/dark duration and produce a flowering stimulus (f... 1
- In some plants, the female gamete develops into embryo without fertilization. This phenomenon is known as : Answer: 4. Parthenogenesis Development of an egg or female gamete into an embryo without fertilisation is parthenogenesis. Autogamy is self-... 1
- What is the fate of the male gametes discharged in the synergid ? Answer: 4. One fuses with the egg and other fuses with central cell nuclei. Key idea: Double fertilisation: both male gametes released into... 1
- Persistent nucellus in the seed is known as : Answer: 2. Perisperm In most seeds the nucellus is used up. In some, such as black pepper and beet, a part of it persists and is called peri... 1
- Placentation, in which ovules develop on the inner wall of the ovary or in peripheral part, is : Answer: 3. Parietal Key idea: Placentation is the arrangement of ovules on the placenta inside the ovary. Marginal: along one margin of a si... 1
- Xylem translocates : Answer: 4. Water, mineral salts, some organic nitrogen and hormones Xylem sap carries mostly water and minerals, but also some organic nitro... 1
- Which of the statements given below is not true about formation of Annual Rings in trees ? Answer: 4. Annual rings are not prominent in trees of temperate region. Key idea: Annual rings are clearest where seasons differ sharply, so... 1
- Which of the following is a commercial blood cholesterol lowering agent ? Answer: 2. Statin Statins (from the yeast Monascus purpureus) inhibit the enzyme that makes cholesterol, so they lower blood cholesterol. Cy... 1
- Concanavalin A is : Answer: 3. a lectin Concanavalin A is a lectin, a carbohydrate-binding protein extracted from jack bean. It is not an alkaloid, an essential... 1
- The correct sequence of phases of cell cycle is : Answer: 4. G ₁ → S → G ₂ → M The cell cycle runs G₁ → S → G₂ → M . G₁ is growth, S is DNA synthesis, G₂ is preparation for division, and M i... 1