GENERAL SCIENCE – II (Biological Science)
MODEL PAPER – I (E/M)
Class: X
Part A & B
Max. Marks: 40
Time: 1.35 Hrs
PART A (Marks: 30)
INSTRUCTIONS:
- Read carefully and understand the question paper.
- Answer the questions under PART-A on a separate answer book.
- Write the answers to the questions under PART-B on the Question Paper itself and attach it to the answer book of PART-A.
SECTION I (3 x 2 = 6 Marks)
INSTRUCTIONS:
- There are three very short answer questions.
- Attempt all questions.
- Each question carries two marks.
- Answer each question in 1 or 2 sentences.
1. What are aerial roots? In which plants do they appear?
Answer:
Aerial roots are roots that grow above the soil. They are typically found in plants like mangroves, orchids, and banyan trees. These roots help in supporting the plant, absorbing moisture, and sometimes in respiration.
2. What happens if insulin is not sufficiently secreted?
Answer:
If insulin is not sufficiently secreted by the pancreas, it can lead to a condition called diabetes mellitus. In this condition, the body cannot properly regulate blood glucose levels, causing high blood sugar and leading to various health complications.
3. State the benefits of adopting micro farming method.
Answer:
Micro farming involves small-scale farming on limited land, which can have several benefits:
- It reduces the cost of production.
- It can be more sustainable and eco-friendly.
- It allows for better crop diversity.
- It promotes organic farming techniques and efficient land use.
SECTION II (3 x 4 = 12 Marks)
INSTRUCTIONS:
- There are four short answer questions.
- Attempt all questions.
- Each question carries four marks.
- Answer each question in 4 to 5 sentences.
4. Specify various applications plants show.
Answer:
Plants have numerous applications in our daily life:
- Food production: Plants provide food for humans and animals.
- Medicinal uses: Many plants like neem, tulsi, and aloe vera are used in traditional medicine.
- Oxygen production: Plants are vital in producing oxygen through photosynthesis.
- Environmental benefits: Plants help in controlling soil erosion, maintaining the water cycle, and providing habitats for animals.
- Industrial uses: Plants like cotton, hemp, and bamboo are used in textiles and construction materials.
5. Analyze the following table and answer the questions given below.
| Serial No | Phylum Name | Type of Circulatory System |
|---|---|---|
| 1 | Protozoa | Brownian motion |
| 2 | Nideria | Vetricular conduction cavity |
| 3 | Platyhelminthes | Open-type circulation system |
| 4 | Nemathelminthes | Mesoceolium |
| 5 | Annelida | Constructing blood vessels |
| 6 | Arthropoda | Closed-type circulation system |
Questions:
- Blood vessels were first formed in which phylum?
Answer: Blood vessels were first formed in the phylum Annelida. - Which organisms exhibit Brownian motion?
Answer: Protozoa exhibit Brownian motion, where particles in the medium move due to collisions with molecules. - What is the name of the type of circulatory system in Hydra, Jellyfish?
Answer: Hydra and Jellyfish (phylum Nideria) have a Ventricular conduction cavity, which is a primitive form of circulatory system. - What is the reason for the presence of an open-type circulatory system in aquatic organisms?
Answer: In aquatic organisms, an open-type circulatory system is common because the external environment (water) helps in the exchange of gases and nutrients directly to tissues, making a closed system less necessary.
6. Write four steps you can take to conserve natural resources in everyday life.
Answer:
- Reduce water wastage: Fix leaky taps and use water-efficient appliances.
- Reduce, Reuse, Recycle: Recycle paper, plastic, and glass and reduce consumption of single-use plastics.
- Use renewable energy: Install solar panels or use energy-efficient lighting to reduce dependence on fossil fuels.
- Save biodiversity: Protect local flora and fauna by planting trees, reducing pollution, and conserving habitats.
SECTION III (2 x 6 = 12 Marks)
INSTRUCTIONS:
- There are four essay questions.
- Attempt only two questions.
- Each question carries six marks.
- Answer each question in 8 or 10 sentences.
7. How can you prove that light is essential for photosynthesis?
Answer:
To prove that light is essential for photosynthesis, we can conduct an experiment using a plant and a beaker of water:
- Place a potted plant in a glass container and expose it to light.
- After a few hours, test the presence of starch in the leaves by boiling them in water to kill the cells, then immerse them in iodine solution.
- The leaf will turn blue-black, indicating the presence of starch formed through photosynthesis.
- Now, place another plant in complete darkness for a few days. After this, repeat the starch test. The leaf will show no starch, proving that in the absence of light, no photosynthesis occurs, and hence, no starch is produced. This experiment demonstrates that light is necessary for photosynthesis.
8. Draw a map of the embryo sac and identify the parts. Explain double fertilization in flowering plants.
Answer:
Diagram of the embryo sac:
The embryo sac is the female gametophyte in flowering plants, and it consists of the following parts:
- Micropyle: The opening through which the pollen tube enters.
- Egg cell: The cell that fuses with one of the sperm cells.
- Synergids: Two cells that help in guiding the pollen tube.
- Antipodal cells: Three cells at the opposite end of the embryo sac.
- Central cell: Contains two polar nuclei.
Double fertilization: Double fertilization is a unique process in flowering plants where two sperm cells from the pollen tube enter the ovule:
- One sperm cell fuses with the egg cell to form a zygote, which develops into the embryo.
- The other sperm cell fuses with the two polar nuclei in the central cell to form a triploid endosperm, which nourishes the developing embryo.
9. Explain Darwin’s theory of natural evolution with examples.
Answer:
Darwin’s theory of natural selection states that organisms with traits that are better suited to their environment are more likely to survive and reproduce, passing those beneficial traits to their offspring. Over generations, this leads to the evolution of species. The key components of Darwin’s theory are:
- Variation: There is natural variation in traits among individuals in a population (e.g., some giraffes have longer necks than others).
- Struggle for existence: Individuals compete for limited resources.
- Survival of the fittest: Organisms with advantageous traits are more likely to survive and reproduce (e.g., giraffes with longer necks can reach food higher in trees).
- Inheritance: The beneficial traits are passed on to the next generation.
An example is the peppered moth in England, where industrial pollution darkened the trees. The darker moths, which were better camouflaged, survived longer than the lighter ones and passed on their traits.
PART B (1 × 10 = 10 Marks)
INSTRUCTIONS:
- Answer all questions.
- Each question carries 1 mark.
- Write capital letters (A, B, C, D) showing the correct answer for the following questions in the brackets against them.
1. Which is the site of photosynthesis in plants?
Options:
(A) Root hairs
(B) Chlorophyll
(C) Mitochondria
(D) Cytoplasm
Correct Answer: (B) Chlorophyll
Explanation:
Photosynthesis primarily occurs in the chloroplasts of plant cells. Chloroplasts contain chlorophyll, a green pigment that absorbs light energy from the sun. This energy is then used to convert carbon dioxide and water into glucose and oxygen. Root hairs are involved in the absorption of water and nutrients, but they do not participate in photosynthesis. Mitochondria are the energy powerhouses of the cell and involved in respiration, not photosynthesis. The cytoplasm is the gel-like substance where many metabolic reactions take place but does not directly participate in photosynthesis.
2. Which is the non-related in the environment?
Options:
(A) Reducing
(B) Recyclable
(C) Reuse
(D) New production
Correct Answer: (D) New production
Explanation:
In environmental conservation, the key concepts include:
- Reducing the use of resources to minimize waste and conserve the environment.
- Recycling involves converting waste materials into reusable materials to avoid depletion of natural resources.
- Reusing means using items multiple times to reduce waste and resource consumption.
New production, on the other hand, involves creating new goods and materials, which often leads to resource depletion and environmental degradation. Hence, it is not related to conservation principles like reducing, recycling, and reusing.
3. Which part is called the junction of the alimentary canal?
Options:
(A) Amoeba
(B) Sponges
(C) Throat
(D) Esophagus
Correct Answer: (C) Throat
Explanation:
The alimentary canal is the tube through which food passes from the mouth to the anus. The throat (or pharynx) serves as the junction between the mouth and the esophagus. It acts as a passageway for both food and air, leading to the esophagus, which then moves food to the stomach. Amoeba and sponges are organisms, not parts of the alimentary canal. The esophagus is a part of the alimentary canal, but it is not the “junction” of the canal.
4. Which of the following are parts of the central nervous system?
Options:
(A) Valve
(B) Artery
(C) Capillary
(D) Brain and spinal cord
Correct Answer: (D) Brain and spinal cord
Explanation:
The central nervous system (CNS) is composed of the brain and the spinal cord. These two components control and coordinate the body’s activities. The other options are parts of the circulatory system, not the nervous system. Valves are found in veins, arteries, and capillaries help circulate blood.
5. Which alkaloid is present in plants?
Options:
(A) Nicotin
(B) Quinine
(C) Nimbin
(D) Caffeine
Correct Answer: (A) Nicotin
Explanation:
Nicotin (or nicotine) is an alkaloid found in the tobacco plant (Nicotiana tabacum). It is a potent chemical that affects the nervous system. The other alkaloids listed are also found in plants:
- Quinine is found in the bark of the cinchona tree and is used to treat malaria.
- Nimbin is found in neem trees and has antimicrobial properties.
- Caffeine is found in coffee, tea, and other plants and acts as a stimulant.
6. Identify the appetite-stimulating hormone?
Options:
(A) Leptin
(B) Ghrelin
(C) Amylase
(D) Secretin
Correct Answer: (B) Ghrelin
Explanation:
Ghrelin is known as the “hunger hormone.” It is produced primarily in the stomach and stimulates appetite by signaling the brain to induce hunger.
- Leptin, on the other hand, is the hormone that signals satiety (fullness) and suppresses appetite.
- Amylase is an enzyme involved in the digestion of carbohydrates, not related to appetite regulation.
- Secretin is a hormone involved in the regulation of digestive juices and enzymes but does not directly stimulate appetite.
7. Identify the asexual process in yeast.
Options:
(A) Binary fission
(B) Parthenogenesis
(C) Budding
(D) Conjugation
Correct Answer: (C) Budding
Explanation:
Budding is the primary method of asexual reproduction in yeast. In this process, a small bud forms on the parent organism and eventually detaches, forming a new individual.
- Binary fission is a method of asexual reproduction seen in bacteria, where a single organism splits into two identical organisms.
- Parthenogenesis is a form of asexual reproduction where offspring are produced without fertilization (seen in some reptiles and insects).
- Conjugation is a sexual process seen in certain organisms like bacteria where genetic material is exchanged.
8. How many cells are formed in the fertilized plant?
Options:
(A) 4
(B) 5
(C) 6
(D) 7
Correct Answer: (D) 7
Explanation:
In flowering plants, after fertilization, the fertilized ovule forms a seed, which contains several cells:
- The zygote develops into the embryo.
- The endosperm is formed by the fusion of a sperm cell with the polar nuclei.
- There are typically 7 cells in the embryo sac after fertilization (including the egg cell, two synergids, three antipodal cells, and one central cell).
Thus, the correct answer is 7.
9. The flow of energy in an ecosystem follows this:
Options:
(A) Down to up
(B) Up to down
(C) In all directions
(D) None of these
Correct Answer: (B) Up to down
Explanation:
In an ecosystem, energy flows in a unidirectional manner from producers (like plants) to herbivores and then to carnivores. This is known as the food chain. The flow of energy is from bottom (producers) to top (consumers) in a trophic pyramid.
- Down to up would suggest energy flows the opposite way, which is not true.
- Energy does not flow “in all directions” or in a random manner.
10. The following is an example of a seedless fruit:
Options:
(A) Grapes
(B) Lemon
(C) Mango
(D) None of these
Correct Answer: (A) Grapes
Explanation:
Grapes are commonly known to be a seedless fruit variety, which means they are cultivated to not develop seeds. This is typically achieved through processes like selective breeding or genetic modification.
- Lemon and Mango are fruits that typically contain seeds, though seedless varieties can exist, they are not as common.
- The answer “None of these” is incorrect because grapes are widely recognized as seedless.
Summary of Answers:
- (B) Chlorophyll
- (D) New production
- (C) Throat
- (D) Brain and spinal cord
- (A) Nicotin
- (B) Ghrelin
- (C) Budding
- (D) 7
- (B) Up to down
- (A) Grapes