1. A male infant was born with an extra X chromosome. The infant was pronounced to be
(A) Klinefelter
(B) Turner
(C) Mon gol
(D) Transgender
2. Which of the following is a true fish?
(A) Dog fish
(B) Star fish
(C) Silverfish
(D) Jellyfish
3. Pick the odd one out:
(A) Night blindness
(B) Scurvy
(C) Xerophthalmia
(D) Colour blindness
4. Identify the modification to which runner, stolon, and sucker belong:
(A) Aerial modification of stem
(B) Subaerial modification of stem
(C) Underground modification of stem
(D) Underground modification of root
5. Identify the narrow-spectrum antibiotic:
(A) Tetraacycline
(B) Chloramphenicol
(C) Streptomycin
(D) Erythromycin
6. Apomixis is
(A) development of plants without fusion of gametes
(B) development of plants in darkness
(C) mixing of characters due to fusion of gametes
(D) effect of low temperature on flowering
7. Identify the starch-containing bodies which are integral part of the chloroplasts in green algae:
(A) Glycogen
(B) Pyrenoid
(C) Carotenoid
(D) Cellulose
8. Which one of the following is not a turgor movement?
(A) Flowers of Portulaca bloom during the day and the petals close at sunset
(B) Opening and closing of stomata
(C) Mimosa pudica droops when touched
(D) Leaf closes in the Venus flytrap when the insect enters
2 MARKS QUESTIONS
9. List any four advantages of biodiesel.
Ans: Bio-diesel has several advantages; some of them are given below- (any four)
It is an agriculture-based fuel substitute.
It can be made from both vegetable oil and animal fats.
It can be used without major modifications in engines.
It does not need a separate infrastructure for storage and delivery.
Handling biodiesel is safer.
Planting of Jatropha curcus will utilize wasteland in our country.
Its combustion emits less carbon monoxide, sulphates, unburnt hydrocarbons, and particulate matter, thus reducing air pollution.
10. Name the respiratory organs of (a) cockroach and (b) earthworm.
Ans:
Cockroach: Tracheae.
Earthworms: Skin on the body
11. Distinguish between a test cross and a reciprocal cross.
Ans: Test cross is the crossing of the F1 progeny with the homozygous recessive parent. Reciprocal cross is the cross in which the sex of the parents is reversed. That is, if in the first cross father was a dwarf and the mother tall, then in the reciprocal cross, the dwarf parent will be female and the tall parent male.
12. State two points of difference between innate immunity and acquired immunity.
Ans:
13. Name the parts of the brain which carry out the following functions:
(a) Maintain balance of body
(b) Carry out reflexes below the neck
(c) Carry out mental activities of thinking, reasoning, memorizing, etc.
(d) Control heartbeat and other involuntary actions
Ans:
Cerebellum
Spinal cord
Cerebral cortex
Medulla oblongata
14. A pregnant woman has to feed her developing embryo; therefore, she needs extra nutrients in her diet. List any four dietary requirements of a pregnant woman.
Ans: The pregnant woman should take,
Extra protein for tissue growth
More calcium and phosphorus are needed to form bones of the baby
More iron is needed to make sufficient blood for the baby
More carbohydrates for herself because extra energy is required to carry out all the building processes linked with the embryo.
15. (a) Give any three adaptations found in flowers to promote cross-pollination.
(b) Give any one adaptation to ensure self-pollination in flowers.
Ans:
Adaptations in flowers to promote cross-pollination are,
Flowers are small, without colour, nectar, or scent.
Flowers produce a large number of pollen grains to allow for wastage when pollen grains are carried by wind to another flower.
The pollen grains are small, light, and sometimes provided with ‘Wings’.
The stigmas are comparatively large, protruding and sometimes hairy, to trap pollen grains from wind, for example, grasses and some cacti.
Self-pollination: Male and female sex organs mature at the same time (homogamy) e.g. groundnut.
16. With the help of a flowchart, list the steps involved in the coagulation of blood.
Ans:
17. List the four steps to summarize the process of energy flow in a food chain.
Ans: The entire process of energy flow can be summarized in the following four steps:
The flow of energy in an ecosystem is always linear or one-way.
At every step in a food chain, the energy received by the organism is also used for its own metabolism and maintenance. The leftover is passed to the next higher trophic level. Thus, energy flow decreases with successive trophic levels.
It follows the ecological thumb rule of 10%.
The number of steps is limited to four or five in a food chain for the transfer of energy.
18. Draw neat and labelled diagrams to show the main difference between epigeal germination and hypogeal germination.
Ans:
19. With the help of sketches and appropriate examples, distinguish between the following pairs:
(a) Corymb and Umbel
(b) Axile and Parietal placentations
Ans:
Corymb and Umbel
Corymb: Lower (older) flowers have longer stalks than the upper younger ones, thus all flowers come to lie at the same level. Eg. Candytuft
Umbel: A Flower with stalks of equal length arising from the same point. Eg. Coriander
Axile and Parietal Placentations
Axile (b) – Ovary is polycarpellary syncarpous, having many chambers and ovules present on the placenta develop from the central axis formed by the fusion of the margins of two or more carpels, e.g. China rose, tomato, bhindi.
(b) List any three anthropogenic causes of soil erosion.
Ans:
The removal of top layers of soil by wind and water is called soil erosion. Soil erosion causes a significant loss of humus and nutrients, resulting in decreased soil fertility.
Anthropogenic causes of soil erosion are,
Deforestation
Poor farming methods
Overgrazing
4 MARKS QUESTIONS
21. (a) What is leghemoglobin? How is it synthesized? Give its function.
(b) Briefly explain the process of nitrogen fixation in nature.
Ans:
Leghaemoglobin is a special protein found in the legume nodules that helps in nitrogen fixation. Leghemoglobin is produced as a result of the interaction between the bacterium and legume roots. Apparently, the Rhizobium gene codes for the Heme part, and the legume root cell gene codes for the Globin moiety. Both the coded products together constitute the final protein leghemoglobin. It helps in nitrogen fixation by acting as an oxygen scavenger so that the enzymes, nitrogenases, then convert N2 to NH3 under anaerobic conditions.
The overall biochemical process involves stepwise reduction of nitrogen to ammonia. The enzyme nitrogenase is a Mo-Fe-containing protein and binds with a molecule of nitrogen (N2) at its binding site. This molecule of nitrogen is then acted upon by hydrogen (from the reduced coenzymes) and reduced in a stepwise manner. It first produces diamide (N2H2), then hydrazine (N2H4), and finally ammonia (2NH3).
NH3 is not liberated by the nitrogen fixers. It is toxic to the cells, and therefore, these fixers combine NH3 with organic acids in the cell and form amino acids. The general equation for nitrogen fixation may be described as follows:
22. (a) (i) State the meaning of sustainable development.
(ii) Mention any four activities which will help in sustainable development.
(b) Define the term ‘endangered species’. Give an appropriate example.
Ans:
Sustainable Development
Sustainable development is the development that meets the needs of the present generation and conserves resources for future generations.
Activities that help in sustainable development
Reducing excessive use of resources and enhancing resource conservation.
Recycling and reuse of waste materials.
Scientific management of renewable resources, especially bio-resources.
Planting more trees.
Green grassy patches are to be interspersed between concrete buildings.
Using more environmentally friendly materials or biodegradable materials.
Use of technologies that are environmentally friendly and based on efficient use of resources.
Endangered species are those that have been reduced in number to a critical level and are facing a high risk of extinction in the near future. E.g., Asiatic lion, Rhinoceros, Asiatic elephant, etc.
23. How is the DNA molecule packaged in an eukaryotic chromosome?
Ans:
At intervals, DNA molecules are coiled around a “core particle,” which is an octamer, that is made of 8 histone proteins forming a ball-like structure.
Each core particle with DNA around it is called a nucleosome. Under the electron microscope, the eukaryotic chromosome looks like a string of beads (string being the DNA molecule and beads the nucleosomes).
The string is then coiled to form a solenoid, and the solenoid is coiled again (supercoiling), ultimately to form the chromosome.
In this way, the long DNA molecule becomes thicker and thicker and shorter and shorter
24. (a) With the help of diagrams, explain binary fission in Amoeba.
(b) Draw a neat diagram of a nerve cell and label the following:
Perikaryon, axon, node of Ranvier, dendrite
Ans:
Binary fission in Amoeba
Nerve cell
25. Answer the following questions:
(a) Name the gall-producing bacteria which can be used to produce transgenics.
(b) Define the term ‘bioremediation’.
(c) State the main objectives of vaccination.
Ans:
Agrobacterium tumefaciens
Bioremediation is the process of cleaning up the environment using living organisms is called bioremediation.
The objective of vaccination is to introduce the attenuated germs into the body. The body then generates a specific population of memory cells. These memory cells can rapidly increase in number on renewed contact with the same antigen and more antibodies can be produced to protect against infection.
26. (a) Draw a neat and labelled diagram of the longitudinal section of an ovule in an angiosperm.
(b) How is an endosperm formed?
Ans:
Ovule of angiosperms
Endosperm formation: The endosperm development begins before embryo development. This is needed to provide the nutritive tissue for the growth of the zygote into an embryo. The primary endosperm cell divides repeatedly and forms an endosperm tissue.
6 MARKS QUESTIONS
27. (a) What are meristematic tissues? Name the types with their location.
(b) Based on their habitats, distinguish between methanogenic and thermoacidophilic bacteria.
(c) Distinguish between androecium of China rose and Pea.
Ans:
Meristematic tissues are constantly dividing, immature and undifferentiated cells without any intercellular spaces. There are three types of meristematic tissue.
Apical meristem: In the root and shoot tips
Intercalary meristem: At the base of leaves or bases of internodes
Lateral meristem: Cambium, which is found between xylem and phloem, as well as in the bark.
Methanogenic and thermoacidophilic bacteria
Methanogenic bacteria that live in sewage and the intestinal tracts of animals
Thermoacidophilic bacteria that live in hot springs.
Androecium of China rose and Pea
Pea flower
China rose
28. (a) Draw a neat diagram of the excretory organs in humans and label the following:
Kidney, ureter, urethra, urinary bladder
(b) Distinguish among ammonotelic, ureotelic, and uricotelic with appropriate examples.
Ans:
Excretory organs in humans
Ammonotelic, ureotelic, and uricotelic: Depending upon the nitrogenous wastes excreted, animals can be classified as ammonotelic, ureotelic, and uricotelic.
Ammonotelic animals produce highly toxic ammonia. Eg. Amoeba
Ureotelic animals produce urea. E.g., mammals, including humans
Uricotelic animals produce uric acid. E.g.. Birds, reptiles, and insects
29. (a) Draw a neat diagram of the female reproductive system in humans and label the following parts:
Uterus, ovary, cervix, vagina
(b) Where do fertilization and implantation take place in the above system?
(c) Name the two female hormones.
(d) State and define the surgical method of birth control in females.
Ans:
Female reproductive system in humans
Fertilization takes place in the fallopian tube, and implantation happens on the walls of the uterus.
Two female hormones are estrogen and progesterone
Tubectomy is the sterilization of a woman by cutting the fallopian tubes and ligating them so that the ovulated egg cannot pass down for fertilization.
30. (a) Explain the biosynthetic phase of photosynthesis with the help of a diagram. Where does this phase take place in plants, and what is the main product formed?
(b) Distinguish between C3 and C4 photosynthesis with respect to (i) CO2 acceptor and (ii) first product of carboxylation.
Ans:
The biosynthetic phase of photosynthesis takes place in the stroma of the chloroplast.
C3 and C4 Photosynthesis
CO2 acceptor: C3 cycle- ribulose bisphosphate or RuBP, C4 plants- phosphoenol pyruvate (PEP)
First product of carboxylation: C3 plants- 3-phosphoglyceric acid (PGA), C4 plants- oxaloacetic acid (OAA).