Worksheet Solutions

Q1. Answer the following questions:

1. The energy currency of cells produced during photosynthesis is ATP (Adenosine Triphosphate).
2. Match the plant types with their nutritional characteristics:
   
   1. Autotrophs – b. Make their own food using sunlight
   2. Heterotrophs – e. Depend on other organisms for food
   3. Parasitic plants – c. Derive nutrients from living host plants
   4. Carnivorous plants – d. Trap and digest insects
   5. Saprophytes – a. Obtain nutrients by decomposing dead matter
3. How does the structure of a plant leaf contribute to its function in photosynthesis?
   
   1. Increased surface area for gas exchange.
   2. Thick waxy cuticle to reduce water loss.
   3. Presence of chloroplasts containing chlorophyll.
   4. All of the above 
4. What is the primary benefit of adding organic matter to soil?
   
   1. Increasing soil pH.
   2. Improving soil structure and aeration
   3. Decreasing soil fertility.
5. What are the special roots of Cuscuta called as?Answer: Haustoria
6. Name the enzymes responsible for the breakdown of the following nutrients:
   
   1. Protein – Pepsin
   2. Fats – Lipase
   3. Carbohydrates – Amylase

1. 1. What is the role of mucus in the digestive system?
      
      1. It helps break down food into smaller particles.
      2. It absorbs nutrients from digested food.
      3. It provides lubrication and protects the lining of the digestive tract.
      4. It secretes enzymes for digestion.
   2. Which of the following is an example of an organism that exhibits holozoic nutrition?
      
      1. Algae
      2. Fungi
      3. Earthworm
      4. Paramecium

Q1. Answer the following questions:

1. 1. 1. How much food can our stomach hold as a whole? Also write the name of the largest gland in the human body.
         

         The stomach can hold about 1 to 1.5 liters of food. The largest gland in the human body is the liver.

      2. What is the length of small and large intestine?
         

         The small intestine is about 6 meters long, and the large intestine is about 1.5 meters long.

      3. Match the following terms with their correct definitions:
         

         Term	Definition
         1. Atom	b. The smallest particle of a substance that retains its chemical properties.
         2. Molecule	c. A substance made up of two or more atoms chemically bonded together.
         3. Element	d. A substance made up of only one type of atom.
         4. Compound	a. A substance made up of two or more different elements chemically combined.
         5. Mixture	e. A combination of two or more substances that are physically mixed together but not chemically combined.

   2. 1. Match the following elements with their correct atomic numbers:
         

         Element	Atomic Number
         1. Helium	a. 2
         2. Sodium	b. 11
         3. Chlorine	c. 17
         4. Aluminium	d. 13

Subjective type questions:

1. 1. Examine the role of nitrogen-fixing bacteria in the Nitrogen cycle and its significance for plant nutrition. How do leguminous plants benefit from this symbiotic relationship?
      

      Nitrogen-fixing bacteria, such as Rhizobium, convert atmospheric nitrogen into a form that plants can use for growth. This process enriches the soil with nitrogen, an essential nutrient for plant development. Leguminous plants benefit from this symbiotic relationship by gaining a direct source of nitrogen, which enhances their growth and reduces the need for nitrogen fertilizers.

   2. Imagine you are a scientist studying a newly discovered microorganism. Describe the criteria you would use to determine whether it is a Prokaryote or a Eukaryote.
      

      To determine if the microorganism is a Prokaryote or a Eukaryote, I would examine the following criteria:

      • Cell structure: Prokaryotes lack a defined nucleus and membrane-bound organelles, whereas Eukaryotes have a well-defined nucleus and membrane-bound organelles.
      • Genetic material: Prokaryotes have a single, circular chromosome, while Eukaryotes have multiple, linear chromosomes.
      • Cell size: Eukaryotic cells are generally larger than Prokaryotic cells.
      • Ribosomes: Prokaryotes have 70S ribosomes, while Eukaryotes have 80S ribosomes.
   3. Imagine you are a plant biologist studying the anatomy of green leaves. Discuss the significance of chlorophyll and stomata.
      

      Chlorophyll is the green pigment in plants that is essential for photosynthesis, the process by which plants convert light energy into chemical energy. Chlorophyll absorbs light, primarily in the blue and red wavelengths, and uses it to convert carbon dioxide and water into glucose and oxygen.

      Stomata are small pores on the surface of leaves that allow for gas exchange. They enable the intake of carbon dioxide and the release of oxygen during photosynthesis. Stomata also play a crucial role in regulating water loss through transpiration, helping to maintain the plant’s water balance.

   4. How might the decline of insect populations due to factors like habitat loss and pesticide use affect insectivorous plants?
      

      The decline of insect populations can significantly impact insectivorous plants, which rely on insects as a primary source of nutrients, particularly nitrogen. Habitat loss and pesticide use reduce the availability of prey, leading to nutrient deficiencies in these plants. This can result in stunted growth, reduced reproductive success, and overall decline in plant health.

   5. Can you think of any examples where saprophytic organisms are beneficial or harmful to humans? Explain your answer.
      

      Saprophytic organisms, such as fungi and bacteria, play a beneficial role in ecosystems by decomposing dead organic matter, recycling nutrients back into the soil, and maintaining soil health. For example, mushrooms and composting bacteria help break down organic waste, enriching the soil with nutrients.

      However, some saprophytic organisms can be harmful to humans. For instance, certain molds can grow on food and produce mycotoxins, which are toxic to humans and animals. Additionally, some saprophytic fungi, like Aspergillus, can cause respiratory infections in individuals with weakened immune systems.

   6. Why is methane production by ruminants a concern?
      

      Methane production by ruminants is a concern because methane is a potent greenhouse gas with a global warming potential much higher than that of carbon dioxide. Ruminants, such as cows and sheep, produce methane during digestion through a process called enteric fermentation. The release of methane contributes significantly to greenhouse gas emissions, which drive climate change and its associated impacts on the environment and human health.

2. 1. Imagine a scenario where an animal has lost all its molars. How might this impact its ability to digest food effectively?
      

      Molars are essential for grinding and chewing food into smaller pieces, which aids in the mechanical digestion process. If an animal loses all its molars, it will struggle to break down food properly, leading to inefficient digestion and possible nutritional deficiencies. The animal may also experience difficulty swallowing and a reduced ability to extract nutrients from its food.

   2. Imagine you are a nutrient molecule travelling through the human digestive system. Describe the journey you would take from the small intestine to being absorbed into the bloodstream. Include the structures involved and the processes that occur along the way.
      

      As a nutrient molecule in the small intestine, I would first encounter the villi, small finger-like projections lining the intestine that increase surface area for absorption. I would pass through the epithelial cells of the villi and enter the capillaries within them. The absorbed nutrient would then travel through the hepatic portal vein to the liver for processing. From the liver, the nutrient would enter the bloodstream and be transported to various cells in the body where it can be utilized for energy, growth, and repair.

   3. What mechanisms ensure that food travels in the correct direction and does not enter the airway?
      

      The mechanisms that ensure food travels in the correct direction and does not enter the airway include the epiglottis, a flap of tissue that closes over the trachea during swallowing, preventing food from entering the respiratory tract. Additionally, coordinated contractions of the esophagus, known as peristalsis, propel food toward the stomach, ensuring it moves in the correct direction.

   4. How does the chewing of food help in the process of digestion in human beings? What is the technical term used for chewing of the food?
      

      Chewing, or mastication, helps in the digestion process by breaking down food into smaller pieces, increasing the surface area for enzymes to act upon. This mechanical breakdown allows for more efficient chemical digestion by salivary enzymes, such as amylase, which begin breaking down carbohydrates in the mouth. Proper chewing also mixes food with saliva, aiding in the formation of a food bolus that can be easily swallowed.

   5. Describe how you can determine the number of electrons in a neutral atom of an element based on its atomic number.
      

      In a neutral atom, the number of electrons is equal to the number of protons, which is represented by the atomic number of the element. Therefore, by knowing the atomic number, you can determine the number of electrons in the atom. For example, if an element has an atomic number of 6, it has 6 protons and, in a neutral state, 6 electrons.

   6. Differentiate between Homogeneous mixtures and Heterogeneous mixtures with the help of suitable examples:
      

      Homogeneous Mixtures	Heterogeneous Mixtures
      These mixtures have a uniform composition throughout.	These mixtures have a non-uniform composition.
      The individual components are not distinguishable.	The individual components are distinguishable.
      Example: Salt dissolved in water (saline solution).	Example: A mixture of sand and iron filings.