Which of the following statements about the autotrophs is incorrect?
They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll
They store carbohydrates in the form of starch
They convert carbon dioxide and water into carbohydrates in the absence of sunlight
They constitute the first trophic level in food chains
In which of the following groups of organisms, food material is broken down outside the body and absorbed?
Mushroom, green plants, Amoeba
Yeast, mushroom, bread mould
Paramecium, Amoeba, Cuscuta
Cuscuta, lice, tapeworm
Select the correct statement
Heterotrophs do not synthesise their own food
Heterotrophs utilise solar energy for photosynthesis
Heterotrophs synthesise their own food
Heterotrophs are capable of converting carbon dioxide and water into carbohydrates
Which is the correct sequence of parts in human alimentary canal?
Mouth → stomach → small intestine → oesophagus → large intestine
Mouth → oesophagus → stomach → large intestine → small intestine
Mouth → stomach → oesophagus → small intestine → large intestine
Mouth → oesophagus → stomach → small intestine → large intestine
If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected?
Proteins breaking down into amino acids
Starch breaking down into sugars
Fats breaking down into fatty acids and glycerol
Absorption of vitamins
The inner lining of stomach is protected by one of the following from hydrochloric acid. Choose the correct one.
Pepsin
Mucus
Salivary amylase
Bile
Which part of alimentary canal receives bile from the liver?
Stomach
Small intestine
Large intestine
Oesophagus
A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains
complex proteins
simple proteins
fats
starch
In which part of the alimentary canal food is finally digested?
Stomach
Mouth cavity
Large intestine
Small intestine
Choose the function of the pancreatic juice from the following
trypsin digests proteins and lipase digests carbohydrates
trypsin digests emulsified fats and lipase proteins
trypsin and lipase digest fats
trypsin digests proteins and lipase emulsified fats
When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due to the presence of
oxygen
carbon dioxide
nitrogen
water vapour
The correct sequence of anaerobic reactions in yeast is
Glucose cytoplasm, Pyruvate mitochondria, Ethanol + Carbon dioxide
Glucose cytoplasm, Pyruvate cytoplasm, Ethanol + Carbon dioxide
Glucose cytoplasm, Pyruvate mitochondria, Lactic acid
Glucose cytoplasm, Pyruvate cytoplasm, Ethanol + Carbon dioxide
Which of the following is most appropriate for aerobic respiration?
Glucose mitochondria, Pyruvate cytoplasm, CO₂ + H₂O + Energy
Glucose cytoplasm, Pyruvate mitochondria, CO₂ + H₂O + Energy
Glucose cytoplasm, Pyruvate + Energy mitochondria, CO₂ + H₂O
Glucose cytoplasm, Pyruvate + Energy mitochondria, CO₂ + H₂O + Energy
Which of the following statement(s) is (are) true about respiration?
(i) During inhalation, ribs move inward and diaphragm is raised
(ii) In the alveoli, exchange of gases takes place
(iii) Haemoglobin has greater affinity for carbon dioxide than oxygen
(iv) Alveoli increase surface area for exchange of gases
(i) and (iv)
(ii) and (iii)
(i) and (iii)
(ii) and (iv)
Which is the correct sequence of air passage during inhalation?
Nostrils → larynx → pharynx → trachea → lungs
Nasal passage → trachea → pharynx → larynx → alveoli
larynx → nostrils → pharynx → lungs
Nostrils → pharynx → larynx → trachea → alveoli
During respiration exchange of gases take place in
trachea and larynx
alveoli of lungs
alveoli and throat
throat and larynx
Which of the following statement (s) is (are) true about heart?
(i) Left atrium receives oxygenated blood from different parts of body while right atrium receives deoxygenated blood from lungs
(ii) Left ventricle pumps oxygenated blood to different body parts while right ventricle pumps deoxygenated blood to lungs
(iii) Left atrium transfers oxygenated blood to right ventricle which sends it to different body parts
(iv) Right atrium receives deoxygenated blood from different parts of the body while left ventricle pumps oxygenated blood to different parts of the body
(i)
(ii)
(ii) and (iv)
(i) and (iii)
What prevents backflow of blood inside the heart during contraction?
Valves in heart
Thick muscular walls of ventricles
Thin walls of atria
All of the above
Single circulation i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by
Labeo, Chameleon, Salamander
Hippocampus, Exocoetus, Anabas
Hyla, Rana, Draco
Whale, Dolphin, Turtle
In which of the following vertebrate group/groups, heart does not pump oxygenated blood to different parts of the body?
Pisces and amphibians
Amphibians and reptiles
Amphibians only
Pisces only
Choose the correct statement that describes arteries.
They have thick elastic walls, blood flows under high pressure; collect blood from different organs and bring it back to the heart
They have thin walls with valves inside, blood flows under low pressure and carry blood away from the heart to various organs of the body
They have thick elastic walls, blood flows under low pressure; carry blood from the heart to various organs of the body
They have thick elastic walls without valves inside, blood flows under high pressure and carry blood away from the heart to different parts of the body.
The filtration units of kidneys are called
ureter
urethra
neurons
nephrons
Oxygen liberated during photosynthesis comes from
water
chlorophyll
carbon dioxide
glucose
The blood leaving the tissues becomes richer in
carbon dioxide
water
heamoglobin
oxygen
Which of the following is an incorrect statement?
Organisms grow with time
Organisms must repair and maintain their structure
Movement of molecules does not take place among cells
Energy is essential for life processes
The internal (cellular) energy reserve in autotrophs is
glycogen
protein
starch
fatty acid
Which of the following equations is the summary of photosynthesis?
\(6CO_2 + 12H_2O \rightarrow C_6H_{12}O_6 + 6O_2 + 6H_2O\)
\(6CO_2 + H_2O + \text{Sunlight} \rightarrow C_6H_{12}O_6 + O_2 + 6H_2O\)
\(6CO_2 + 12H_2O + \text{Chlorophyll} + \text{Sunlight} \rightarrow C_6H_{12}O_6 + 6O_2 + 6H_2O\)
\(6CO_2 + 12H_2O + \text{Chlorophyll} + \text{Sunlight} \rightarrow C_6H_{12}O_6 + 6CO_2 + 6H_2O\)
Choose the event that does not occur in photosynthesis
Absorption of light energy by chlorophyll
Reduction of carbon dioxide to carbohydrates
Oxidation of carbon to carbon dioxide
Conversion of light energy to chemical energy
The opening and closing of the stomatal pore depends upon
oxygen
temperature
water in guard cells
concentration of CO₂ in stomata
Choose the forms in which most plants absorb nitrogen
(i) Proteins
(ii) Nitrates and Nitrites
(iii) Urea
(iv) Atmospheric nitrogen
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iv)
Which is the first enzyme to mix with food in the digestive tract?
Pepsin
Cellulase
Amylase
Trypsin
Which of the following statement(s) is (are) correct?
(i) Pyruvate can be converted into ethanol and carbon dioxide by yeast
(ii) Fermentation takes place in aerobic bacteria
(iii) Fermentation takes place in mitochondria
(iv) Fermentation is a form of anaerobic respiration
(i) and (iii)
(ii) and (iv)
(i) and (iv)
(ii) and (iii)
Lack of oxygen in muscles often leads to cramps among cricketers. This results due to
conversion of pyruvate to ethanol
conversion of pyruvate to glucose
conversion of glucose to pyruvate
conversion of pyruvate to lactic acid
Choose the correct path of urine in our body
kidney → ureter → urethra → urinary bladder
kidney → urinary bladder → urethra → ureter
kidney → ureters → urinary bladder → urethra
urinary bladder → kidney → ureter → urethra
During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the
cytoplasm
chloroplast
mitochondria
golgi body
Name the following:
(a) The process in plants that links light energy with chemical energy
(b) Organisms that can prepare their own food
(c) The cell organelle where photosynthesis occurs
(d) Cells that surround a stomatal pore
(e) Organisms that cannot prepare their own food
(f) An enzyme secreted from gastric glands in the stomach that acts on proteins
(a) Photosynthesis
(b) Autotrophs
(c) Chloroplast
(d) Guard Cells
(e) Heterotrophs
(f) Pepsin
“All plants give out oxygen during day and carbon dioxide during night”. Do you agree with this statement? Give reason.
During daytime, the rate of photosynthesis is more than the rate of respiration, so oxygen is released. At night, photosynthesis stops and only respiration occurs, causing release of carbon dioxide.
How do the guard cells regulate opening and closing of stomatal pores?
Guard cells absorb water and become turgid, causing stomatal pores to open. When they lose water and become flaccid, the stomatal pores close.
Two green plants are kept separately in oxygen-free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.
The plant kept in continuous light will live longer because it can photosynthesise and produce oxygen required for respiration.
If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.
This indicates that the rate of respiration is higher than the rate of photosynthesis. Carbon dioxide produced in respiration is used in photosynthesis, so no CO₂ is released normally. If CO₂ is released, photosynthesis is very slow or not occurring.
Why do fishes die when taken out of water?
Fishes respire through gills, which can absorb oxygen only when it is dissolved in water. Out of water, they cannot absorb oxygen and die.
Differentiate between an autotroph and a heterotroph.
| Autotroph | Heterotroph |
|---|---|
| 1. Organisms that prepare their own food. | 1. Organisms dependent on others for food. |
| 2. They have chlorophyll. | 2. They lack chlorophyll. |
Autotrophs prepare their own food and possess chlorophyll, while heterotrophs depend on other organisms for food and lack chlorophyll.
Is 'nutrition' a necessity for an organism? Discuss.
Nutrition is necessary because it provides energy for metabolic processes, supports growth and repair of cells, and helps develop resistance against diseases.
What would happen if green plants disappear from earth?
All herbivores would die due to starvation, followed by carnivores. Life would collapse because green plants are the main source of energy for all organisms.
Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer.
No, the plant will not remain healthy because:
(a) It will not get oxygen for respiration.
(b) It will not get carbon dioxide for photosynthesis.
(c) Transpiration will stop, hindering upward movement of water and minerals.
How does aerobic respiration differ from anaerobic respiration?
| Aerobic respiration | Anaerobic respiration |
|---|---|
| 1. Oxygen is utilised. | 1. Oxygen is not required. |
| 2. Occurs in cytoplasm and mitochondria. | 2. Occurs only in cytoplasm. |
| 3. End products: carbon dioxide and water. | 3. End products: lactic acid or ethanol and carbon dioxide. |
| 4. More energy released. | 4. Less energy released. |
Aerobic respiration uses oxygen, occurs in cytoplasm and mitochondria, produces CO₂ and water, and releases more energy. Anaerobic respiration occurs without oxygen, happens only in cytoplasm, produces lactic acid or ethanol, and releases less energy.
Match the words of Column (A) with those of Column (B).
| Column (A) | Column (B) |
|---|---|
| (a) Phloem | (i) Excretion |
| (b) Nephron | (ii) Translocation of food |
| (c) Veins | (iii) Clotting of blood |
| (d) Platelets | (iv) Deoxygenated blood |
(a) (ii)
(b) (i)
(c) (iv)
(d) (iii)
Differentiate between an artery and a vein.
| Artery | Vein |
|---|---|
| 1. Thick, elastic muscular walls | 1. Thin, non-elastic walls |
| 2. Narrow lumen | 2. Wide lumen |
| 3. Carry blood from heart to body parts | 3. Carry blood from body parts to heart |
| 4. Carry oxygenated blood (except pulmonary artery) | 4. Carry deoxygenated blood (except pulmonary vein) |
Arteries have thick elastic walls, a narrow lumen, carry blood from the heart, and usually carry oxygenated blood. Veins have thin non-elastic walls, a wide lumen, carry blood to the heart, and usually carry deoxygenated blood.
What are the adaptations of leaf for photosynthesis?
Leaves have a large surface area, are arranged to avoid overlapping, contain many veins for quick transport, possess numerous stomata, and have more chloroplasts on the upper surface.
Why is small intestine in herbivores longer than in carnivores?
Digestion of cellulose takes longer. Herbivores need a longer small intestine for complete digestion of cellulose, whereas carnivores do not digest cellulose and thus have a shorter intestine.
What will happen if mucus is not secreted by the gastric glands?
Mucus protects the inner lining of the stomach from hydrochloric acid and enzymes. Without mucus, the stomach lining would erode, leading to acidity and ulcers.
What is the significance of emulsification of fats?
Emulsification breaks large fat globules into smaller ones, increasing efficiency of fat-digesting enzymes.
What causes movement of food inside the alimentary canal?
Rhythmic contraction and relaxation of muscles of the alimentary canal cause peristalsis, which pushes food forward.
Why does absorption of digested food occur mainly in the small intestine?
Because digestion is completed in the small intestine, its inner lining has villi that increase surface area, and it is richly supplied with blood vessels that transport absorbed food.
Match Group (A) with Group (B).
| Group (A) | Group (B) |
|---|---|
| (a) Autotrophic nutrition | (i) Leech |
| (b) Heterotrophic nutrition | (ii) Paramecium |
| (c) Parasitic nutrition | (iii) Deer |
| (d) Digestion in food vacuoles | (iv) Green plant |
(a) (iv)
(b) (iii)
(c) (i)
(d) (ii)
Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?
Aquatic organisms obtain oxygen from dissolved oxygen in water, which is much less than oxygen in air. Hence they breathe faster to meet oxygen needs.
Why is blood circulation in human heart called double circulation?
Because blood passes twice through the heart in one complete cycle: once through the right side carrying deoxygenated blood, and once through the left side carrying oxygenated blood.
What is the advantage of having a four-chambered heart?
It completely separates oxygenated and deoxygenated blood, preventing mixing and ensuring efficient oxygen supply. This is essential for animals with high energy needs.
Mention the major events during photosynthesis.
(a) Absorption of light energy by chlorophyll
(b) Conversion of light energy to chemical energy
(c) Splitting of water molecules into \( H_2, O_2 \) and electrons
(d) Reduction of \( CO_2 \) to carbohydrates
In each of the following situations, state what happens to the rate of photosynthesis:
(a) Cloudy days
(b) No rainfall in the area
(c) Good manuring in the area
(d) Stomata get blocked due to dust
(a) Decreases
(b) Decreases
(c) Increases
(d) Decreases
Name the energy currency in living organisms. When and where is it produced?
Adenosine triphosphate (ATP) is the energy currency. It is produced during respiration in living organisms and during photosynthesis in plants.
What is common for Cuscuta, ticks and leeches?
All are parasites; they derive nutrition from plants or animals without killing them.
Explain the role of mouth in digestion of food.
(a) Food is crushed into small pieces by the teeth.
(b) It mixes with saliva and the enzyme amylase breaks down starch into sugars.
(c) Tongue helps in thorough mixing of food with saliva.
What are the functions of gastric glands present in the wall of the stomach?
(a) Production of pepsin enzyme that digests proteins.
(b) Secretion of mucus for protection of the inner lining of the stomach.
(c) Secretion of hydrochloric acid.
Match the terms in Column (A) with those in Column (B).
| Column (A) | Group (B) |
|---|---|
| (a) Trypsin | (i) Pancreas |
| (b) Amylase | (ii) Liver |
| (c) Bile | (iii) Gastric glands |
| (d) Pepsin | (iv) Saliva |
(a) — (i)
(b) — (iv)
(c) — (ii)
(d) — (iii)
Name the correct substrates for the following enzymes:
(a) Trypsin
(b) Amylase
(c) Pepsin
(d) Lipase
(a) Protein
(b) Starch
(c) Protein
(d) Fats
Why do veins have thin walls as compared to arteries?
Arteries carry blood under high pressure from the heart, so their walls are thick and elastic. Veins carry blood at lower pressure and therefore have thin walls with valves to ensure one-way flow.
What will happen if platelets were absent in the blood?
Blood clotting would be affected, leading to excessive bleeding even from minor injuries.
Plants have low energy needs as compared to animals. Explain.
Plants do not move. They also have many dead cells like sclerenchyma, so they require less energy compared to animals.
Why and how does water enter continuously into the root xylem?
Root cells are in contact with soil and actively take up ions, increasing ion concentration inside the root. This increases osmotic pressure, causing continuous movement of water from soil into the roots.
Why is transpiration important for plants?
(a) It helps in absorption and upward movement of water and minerals from roots to leaves.
(b) It prevents plants from overheating.
How do leaves of plants help in excretion?
Some waste materials are stored in vacuoles of mesophyll and epidermal cells. When old leaves fall, the wastes are removed along with them.
Explain the process of nutrition in Amoeba.
1. Ingestion: Amoeba engulfs food particles such as algae and small organisms by extending finger-like projections called pseudopodia. These pseudopodia surround the food and form a food vacuole.
2. Digestion: Inside the food vacuole, digestive enzymes are secreted that break down complex food substances into simpler, absorbable forms.
3. Absorption: The digested food is absorbed directly into the cytoplasm, where it is utilized for growth, repair, and producing energy.
4. Assimilation: Absorbed nutrients become part of the cell’s structure or are used to produce energy for vital activities.
5. Egestion: The undigested food material is expelled from the body by the vacuole moving near the cell surface and rupturing.
Describe the alimentary canal of man.
The human alimentary canal is a long, muscular tube extending from the mouth to the anus. Its major parts include:
1. Mouth cavity: Food is chewed and mixed with saliva, which contains amylase for starch digestion.
2. Oesophagus: A muscular tube through which food passes to the stomach by peristalsis.
3. Stomach: A sac-like organ that secretes hydrochloric acid, pepsin, and mucus. Here, proteins are partially digested.
4. Small intestine: Main site for digestion and absorption of nutrients. Enzymes from pancreas and bile from liver aid digestion. Villi increase the surface area for absorption.
5. Large intestine: Absorbs water and salts. Undigested food is compacted into faeces.
Explain the process of breathing in man.
1. Passage of air: Air enters through nostrils, passes into nasal cavity, then through pharynx, larynx, trachea, bronchi, bronchioles, and finally reaches the alveoli in the lungs.
2. Gaseous exchange: In alveoli, oxygen diffuses into blood and carbon dioxide diffuses out into the alveolar air due to concentration gradients.
3. Role of diaphragm: During inhalation, the diaphragm contracts and flattens, increasing thoracic volume and drawing air into the lungs. During exhalation, it relaxes and becomes dome-shaped, pushing air out.
4. Function of rib muscles and alveoli: Intercostal muscles lift the ribs during inhalation and lower them during exhalation, helping in ventilation. Alveoli provide a large surface area for gaseous exchange.
Explain the importance of soil for plant growth.
1. Anchoring the plant: Soil provides physical support to plants by anchoring their roots firmly.
2. Source of water and minerals: Soil supplies essential water and minerals required for various metabolic processes.
3. Availability of oxygen for root respiration: Air spaces in soil provide oxygen for respiration of root cells.
4. Symbiotic association with microbes: Soil hosts microbes that help in nitrogen fixation and decomposition, enriching soil fertility for plant growth.
Draw the diagram of alimentary canal of man and label the following parts: Mouth, Oesophagus, Stomach, Intestine.
The alimentary canal of man consists of:
1. Mouth: Opening through which food enters the body.
2. Oesophagus: A muscular tube that carries food to the stomach by peristalsis.
3. Stomach: A sac-like organ where proteins are digested.
4. Intestine (Small and Large): Small intestine digests and absorbs nutrients; large intestine absorbs water.
(Diagram should depict the labelled structures as described.)
How do carbohydrates, proteins and fats get digested in human beings?
Carbohydrate digestion: Begins in the mouth where salivary amylase breaks starch into maltose. In the small intestine, pancreatic amylase converts starch into simple sugars, and intestinal enzymes convert them into glucose.
Protein digestion: In the stomach, pepsin breaks proteins into peptides. In the small intestine, trypsin and peptidases convert them into amino acids.
Fat digestion: Bile emulsifies fats into small droplets. Lipase from pancreas and intestinal glands breaks fats into fatty acids and glycerol.
Explain the mechanism of photosynthesis.
1. Absorption of light energy by chlorophyll: Chlorophyll absorbs sunlight and becomes activated.
2. Conversion of light energy to chemical energy: Activated chlorophyll converts light energy into chemical energy in the form of ATP and NADPH.
3. Splitting of water: Light energy splits water into \( H_2 \), \( O_2 \), and electrons. Oxygen is released, while hydrogen is used in the next stage.
4. Reduction of carbon dioxide: CO2 is reduced to carbohydrates using hydrogen and chemical energy.
Explain the three pathways of breakdown in living organisms.
1. Aerobic respiration: Pyruvate produced during glycolysis enters mitochondria and breaks down into \( CO_2 \), \( H_2O \), and releases large amounts of energy.
2. Anaerobic respiration (yeast): Pyruvate is converted into ethanol, \( CO_2 \), and small amounts of energy.
3. Anaerobic respiration (muscles): During vigorous activity, pyruvate converts into lactic acid and energy in absence of oxygen, causing muscle cramps.
Describe the flow of blood through the heart of human beings.
1. Right side of the heart: Deoxygenated blood from the body enters the right atrium via vena cava. It moves to the right ventricle, which pumps it to the lungs through the pulmonary artery.
2. Gas exchange in lungs: In the lungs, blood releases CO2 and absorbs oxygen.
3. Left side of the heart: Oxygenated blood returns via pulmonary veins to the left atrium. It flows to the left ventricle, which pumps it to the entire body through the aorta.
This double circulation ensures separation of oxygenated and deoxygenated blood.
Describe the process of urine formation in kidneys.
1. Filtration: Blood enters the glomerulus where water, urea, salts, and small molecules are filtered into Bowman’s capsule forming filtrate.
2. Reabsorption: Useful substances such as glucose, amino acids, and water are reabsorbed back into blood from the renal tubule.
3. Secretion: Additional wastes like ions and toxins are secreted into the tubule from blood.
The remaining fluid becomes urine, which passes into the ureter and is stored in the urinary bladder before excretion.