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MOCK EXAMINATION - 2024 BIOLOGY GRADE: 10 TIME: 2 HOURS DATE: 05/02/2024 MAX. MARKS: 80 ____________________________________________________________________________ INSTRUCTIONS [The time stated above is the time allowed for writing the examination. In addition, the first 15 minutes will be the time given for reading the question paper] This question paper is divided into two sections. Section A is compulsory. Attempt any four questions from Section B. The intended marks for questions or parts of questions are given in brackets []. ____________________________________________________________________________ SECTION A (40 MARKS) (Answer all questions in this section) Question 1 Choose the correct answers to the questions from the given options. (Do not copy the questions, write the correct answer only.) [15] (i) ............... gives cooling effect in plants. (a) Transpiration (b) Evaporation (c) Translocation (d) Transportation (ii) Permanently open structures seen on the barks of old woody stems : (a) Stomata. (b) Hydathodes. (c) Lenticels. (d) Epidermal pores. (iii) The hormone that promotes ripening of fruits is (a) ethylene (b) gibberellin (c) cytokinine (d) auxin Page 1 of 15 . (iv) Ozone hole results in (a) UV radiation reaching the earth (b) increase in skin cancer (c) cataract (d) all the above (v) Which of the following blood vessels in man carries with it the least concentration of urea? (a) Hepatic vein (b) Hepatic artery (c) Renal artery (d) Renal vein (vi) Assertion: Imbibition involves the absorption of water molecules by living or dead plant cells through their hydrophilic surfaces. Reason: When seeds germinate, the seed coat breaks due to the imbibition pressure. (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true, but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. (vii) From which of these tears come out? (a) Eyeball (b) Aqueous chamber (c) Lachrymal glands (d) Vitreous chamber (viii) Reabsorption of all the glucose and most of the water occurs in (a) distal convoluted tubule (b) proximal convoluted tubule (c) Loop of Henle (d) collecting duct (ix) A gland having endocrine as well as exocrine function is (a) pituitary (b) thyroid (c) adrenal (d) pancreas Page 2 of 15 (x) The primary source of Chlorofluorocarbons is (a) vehicular emissions (b) refrigeration equipment s (c) industrial effluents (d) domestic sewage (xi) The cell component visible only during cell division ________. (a) Mitochondria (b) Chloroplast (c) Chromosome (d) Chromatin (xii) When two atria contract simultaneously and result in the blood pumping into ventricles, this is called(a) arterial diastole (b) ventricular systole (c) ventricular diastole (d) arterial systole (xiii) Cretinism and myxoedema are due to (a) hyposecretion of thyroxine (b) hypersecretion of thyroxine (c) hypersecretion of growth hormone (d) hyposecretion of growth hormone (xiv) Equatorial plane is formed in: (a) Anaphase (b) Metaphase (c) Telophase (d) Interphase (xv) Which of the following parts of human ear contribute in hearing? (a) Semicircular canals, utriculus and sacculus (b) Eustachian tube, tympanum and utriculus (c) Perilymph, ear ossicles and semicircular canals (d) Cochlea, ear ossicles and tympanum Page 3 of 15 Question 2 (i) Complete the following paragraph by filling in the blanks marked (a) to (e) with the appropriate word/ term. [5] Blood in human beings flows (a) .twice. in the heart before it completes (b) one.. round. It is comprised of one short pathway, i.e. (c) .pulmonary.... circulation and another long pathway, i.e. (d) systemic circulation. Due to this reason, the blood flow in humans is known as (e)double circulation. (ii) Identify the odd one out from the following terms and name the category to which other three belong. [5] (a) Goiter, Cretinism, Myxoedema, Acromegaly Hormonal disorders related to the thyroid gland (b) Ovary, Fallopian Tube, Ureter, Uterus Reproductive organs/system (c) Myopia, Hypermetropia, Xerophthalmia, Astigmatism Eye disorders (d) Eutrophication, Oil spills, Algal bloom, Acid rain Cause or effect of water pollution (e) Testes, Prostate gland, Seminal vesicle, Cowper s gland Accessory Male reproductive organs (iii). Arrange and rewrite the terms in each group in the correct order so as to be in a logical sequence beginning with the term that is underlined. [5] (a) Root hair, Endodermis, Epidermis, Xylem, Cortex. Root hair(epidermis), cortex, endodermis, xylem (b) Chloroplast, Thylakoids, Grana, Stroma Chloroplast, stroma, Grana, thylakoids (c) Axon, Nissl s granules, Cyton, Dendrites AVOID Nissil granule, cyton, dendrites, axon Adrenal gland, Epinephrine, Pituitary gland, Adrenocorticotropic. Pituitary gland, Adrenocorticotropic, Adrenal gland, Epinephrine (e) Genes, Chromosome, Allele, Chromatin Allele, Genes, chromatin, chromosome (d) Page 4 of 15 (vi). Name the following [5] (a) The process by which kidneys regulate the water content of the body. (b) Shrinkage of protoplasm when a cell is kept in a hypertonic solution. (c) The plant on which Mendel had worked. (d) The hormone which prepares the body for defence. (e) The tube which connects the cavity of the middle ear with the throat. (a) Osmoregulation (b) Plasmolysis (c) Pea plant (d) Adrenaline (e) Eustachian tube (v) Match the items given in Column I with the most appropriate ones in Column II and rewrite the correct matching pairs. [5] Column I Column II A. Macula lutea/retina 1. Memory B. iodopsin/color vision 2. Haploid C. Sneezing/simple reflex 3. Colour vision D. Sperm/haploid 4. Simple reflex E. Cerebrum/memory 5. Retina 6. Hindbrain 7. Lens SECTION B (40 MARKS) (Answer Any FOUR questions in this section) Question 3 (i) Write the names of four nitrogenous bases in a DNA molecule.? Adenine, Thymine, Cytosine,Guanine Page 5 of 15 [1] (ii) (iii) Given is a diagram representing a stage during mitotic cell division in an animal cell. [2] (a) Identify the stage. Give a reason to support your answer. \prophase\duplicated centrosomes move towards the poles (b) Name the cell organelle that forms the aster.-centrosome The following diagram demonstrates a physiological process taking place in green plants. The whole set up was placed in bright sunlight for several hours. Study the diagram and answer the questions that follow. [2] (a) What aspect of the physiological process is being examined? Oxygen is produced through the process of photosynthesis (b) Write the chemical equation to represent the process. 6 C O 2 + 12 H 2 O C h l o r o p h y l l S u n l i g h t----- C 6 H 12 O 6 + 6 H 2 O + 6 O 2 (iv) State any two reasons for selecting garden pea by Gregor Johann Mendel for his experiments. [2]\ Variability in Traits Pea plants are capable of self-fertilization (v) The diagram given below is that of a structure present in a human kidney. Study the same and answer the questions that follow: (a) Name the structure represented in the diagram.-Nephron Page 6 of 15 [3] What is the liquid entering part 1 called? Glomerular filtrate (c) What is the fluid that comes to part 2 called? Name the main nitrogenous waste in it. Urine/ urea (b) Question 4 (i) What is a portal vein? [1] A vein that does not carry deoxygenated blood directly to the heart but forms a network of capillaries on another organ before reaching the heart is called portal vein.it begins and ends with capillaries. Taking the example of giraffe, explain use and disuse of organs. [2] Use and disuse of organs in giraffe: Use and disuse theory suggests that organs develop or degenerate based on their use or disuse. In the case of a giraffe, the long neck is developed through the continuous stretching and use, while less-used organs may undergo degeneration. (ii) Point out differences between an artery and a vein. [2] Artery carries oxygenated blood (except pulmonary artery), while veins carry deoxygenated blood (except pulmonary vein). Arteries have thick and elastic muscular walls, while veins have thinner muscular walls Page 7 of 15 (iii) Define -Allele and gene ? Allele: A variant form of a gene. [2] Gene: A segment of DNA that codes for a specific trait (iv) The diagram given below represents a stage during cell division. Study the same and answer the questions that follow: [3] a. Name the type of cell division that occurs during: i. Replacing old leaves by new ones.-mitosis ii. Formation of gametes.-meiosis b. What is the stage that comes before the stage shown in the diagram? prophase Question 5 (i) Give scientific reason for : Plants growing in fertilized soil are often found to wilt if the soil is not adequately watered. [1] . Fertilized soil provides an increased concentration of nutrients. In the absence of adequate water, plants may experience osmotic stress. The high concentration of solutes in the soil, due to fertilization, can lead to a lower water potential in the soil solution. As a result, water moves out of the plant (exosmosis) cells into the soil, causing the cells to lose turgor pressure and the plant to wilt. (ii) Differentiate between the following based on what is indicated within the brackets: Sensory and Motor neuron (function). [2] Transmit signals from sensory receptors (such as those in the skin, eyes, ears) to the central nervous system (CNS). Transmit signals from the central nervous system (CNS) to effectors (muscles or glands) to initiate a response. (iii) The diagram given below represents the parts of the human ear. [2] Page 8 of 15 (a) What is the function of the parts marked 2? Dynamic balance (b) Why is it harmful to use a pin or any sharp object to remove the wax from the ear? The ear canal contains sensitive structures, including the eardrum. Inserting a pin can damage the eardrum or other structures, leading to more severe issues such as hearing loss, dizziness, or ear infections. (iv) Write two effects of soil pollution. [2] Soil pollutants can negatively affect the fertility of the soil and hinder essential microbial activities. This can lead to reduced crop growth, lower agricultural productivity, and poor crop quality. Soil pollutants like pesticides can percolate and contaminate groundwater. (v) The diagram shows an experimental set-up to demonstrate and measure a particular physiological phenomenon in plants. [3] a. What is the apparatus called as ? Ganong s potometer b. What happens to the movement of air bubbles if the apparatus is kept under following conditions: (a) In dark (b) In bright sunlight (a) In Dark: The rate of transpiration decreases. This is because transpiration is largely dependent on light, and in the absence of light, the stomata may close, reducing the movement of air bubbles. - (b) In Bright Sunlight: The rate of transpiration increases. The presence of Page 9 of 15 light stimulates the opening of stomata, leading to an increased movement of air bubbles. c. Based on your answers in part (b) state two factors which affect the rate of transpiration and how they affect the rate? Temperature: Higher temperatures generally increase the rate of transpiration. As temperature rises, water molecules gain more kinetic energy, leading to increased evaporation from the leaf surface. Humidity: Higher humidity reduces the rate of transpiration. In humid conditions, the air is already saturated with moisture, creating a lower concentration gradient for water vapor to move out of the leaf. Question 6 (i) Name the vascular tissues which conduct water and translocate food. [1] Conduct water-xylem/translocate food-phloem (ii) What is meant by power of accommodation? Name the muscles of the eye responsible for the same. [2] The power of accommodation refers to the ability of the eye to adjust its focus to see objects at different distances clearly. The ciliary muscles, located in the eye, are responsible for the power of accommodation. (iii) State any two harmful effects of acid rain. [2] Damage to Aquatic Ecosystems: Acid rain can lead to the acidification of water bodies, such as lakes and rivers. This can harm aquatic life, particularly fish and other organism s sensitive to changes in water pH. Deterioration of Buildings and Structures: The acidic nature of rainwater can contribute to the deterioration of buildings, monuments, and structures made of limestone, marble, or concrete. Acid rain accelerates the corrosion and degradation of these materials. (iv) Study the diagram given below and then answer the questions that follow : [2] Page 10 of 15 a. Name the region in the kidney where the above structure is present.-renal cortex b. Name the parts labelled 1-Afferent arteriole, 2-glomerulus, 3-bowman s capsule and 4-efferent arteriole. c. Name the stages involved in the formation of urine. Ultrafiltration, Reabsorption, tubular Secretion. (v) Draw a neat, labelled diagram of the cross section of a blood vessel that helps us feel our pulse. [3] Question 7 (i) How are root hairs adapted for absorption of water from the soil? [1] Root hairs increase the surface area available for absorption, enhancing the contact with water in the soil (ii) The diagram given below represents a defect of vision of the human eye: [2] Page 11 of 15 a. Identify the defect and mention the cause of it.-Hyperopia/ eyeball too short from front to back/ lens is too flat b. Draw a neat, labelled diagram to show how this defect can be rectified. make sure the lens is named and three rays with arrows (iii) The figure given below represents an experiment to demonstrate a particular aspect of photosynthesis. The alphabet A represents a certain condition inside the flask. [2] What is the aim of the experiment? That carbon dioxide is essential for photosynthesis (b) Identify the special condition inside the flask. KOH is kept to absorb carbondioxide (a) (iv) Before performing starch test on leaf, it is boiled. Why? [2] To test a leaf for starch, the leaf is boiled in water to to kill the cells. It is then boiled in Methylated spirit to remove chlorophyll. The leaf is dipped in warm water to soften it (V) The diagram given below represents the ventral view of the female reproductive system: [3] Page 12 of 15 (a) Label the parts indicated by guidelines 1-8. (b) What happens to the uterus if fertilization takes place? If fertilization takes place, the uterus undergoes changes to support the developing embryo. The fertilized egg (zygote) implants into the endometrium of the uterus, and the uterus provides a suitable environment for the development of the fetus during pregnancy Question 8 (i) State Mendel s law of segregation. [1] According to the law of segregation, only one of the two gene copies present in an organism is distributed to each gamete (egg or sperm cell) that it makes, and the allocation of the gene copies is random. (ii) Describe ultrafiltration? [2] Ultrafiltration-Ultrafiltration involves filtration of the blood which takes place in the glomerulus. The blood containing urea from the afferent arteriole enters the glomerulus under high pressure. The high pressure is created because the efferent arteriole is narrower than the afferent arteriole. The high pressure causes the liquid part of the blood to filter out from the glomerulus into the renal tubule. This filtrate is known as 'glomerular filtrate'. Glomerular filtrate consists of water, urea, salts, glucose, and other plasma solutes. Blood corpuscles, proteins, and other large molecules remain behind in the glomerulus. Page 13 of 15 (iii) Study the figure and answer the following. [2] (a) What is depicted in the figure? Negative geotropism (b) Explain the process. When the stem grows away from the earth's gravitational forces, it is known as negative geotropism (iv) Explain carbon cycle. [2] The carbon cycle is a natural biogeochemical process that involves the movement of carbon through various reservoirs, including the atmosphere, oceans, soil, and living organisms. Processes include photosynthesis by plants (carbon uptake), respiration by living organisms (carbon release), decomposition of organic matter, combustion of fossil fuels, and exchange of carbon between the atmosphere and oceans.. (vi) The diagram given below represents the human heart in one phase the cardiac cycle. Study the same and answer the questions that follow: Page 14 of 15 [3] (a) Name the phase.-ventricular systole (b) Label the parts 1-pulmonary artery, 2-superior vena cava, and 3-aorta (c) Which part of the heart is contracting in this phase? Give a reason to support your answer. Ventricles/semilunar valves are open ---------------------------------------------------------------------------------------------------------- Page 15 of 15
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