Mix Examples - Life Processes Questions in English

(A) Autotrophs are organisms that produce their own food through the process of photosynthesis.
Photosynthesis requires sunlight,chlorophyll,carbon dioxide,and water to synthesize carbohydrates.
Therefore,the statement that they convert carbon dioxide and water into carbohydrates in the absence of sunlight is incorrect,as sunlight is an essential requirement for this process.
Autotrophs store excess carbohydrates as starch in plants.
They form the base of the food chain,representing the first trophic level.

(B) Organisms that break down food material outside the body and then absorb the nutrients are known as saprotrophs.
Saprotrophic nutrition involves the secretion of digestive enzymes onto dead and decaying organic matter, which breaks down complex food substances into simpler forms externally.
$Yeast$, $mushroom$, and $bread$ $\text{mould}$ $(Rhizopus)$ are classic examples of saprotrophic organisms.
In contrast, $Amoeba$ and $Paramecium$ exhibit holozoic nutrition (ingestion), while $Cuscuta$, $lice$, and $tapeworm$ are parasites that derive nutrients from a living host.

(C) Heterotrophs are organisms that cannot produce their own food through processes like photosynthesis.
Instead,they rely on other organisms (plants or animals) for their nutrition.
Autotrophs,on the other hand,are capable of synthesizing their own food using solar energy to convert carbon dioxide and water into carbohydrates.
Therefore,the statement that heterotrophs do not synthesise their own food is correct.

(D) The human alimentary canal is a continuous tube that begins at the mouth and ends at the anus.
Following the path of food ingestion and digestion,the correct sequence is:
$1$. Mouth (Ingestion)
$2$. Oesophagus (Food pipe)
$3$. Stomach (Mixing and digestion)
$4$. Small intestine (Absorption of nutrients)
$5$. Large intestine (Absorption of water and waste elimination)
Therefore,the correct sequence is: Mouth $\to$ oesophagus $\to$ stomach $\to$ small intestine $\to$ large intestine.

(A) Salivary amylase is an enzyme present in saliva that initiates the chemical digestion of carbohydrates in the mouth.
It acts on starch,a complex polysaccharide,and breaks it down into simpler sugars like maltose.
If salivary amylase is absent,the breakdown of starch into sugars will be significantly affected,as this process begins in the oral cavity.

(B) The stomach lining secretes mucus,which forms a protective barrier against the highly acidic environment created by hydrochloric acid $(HCl)$.
$HCl$ is essential for activating pepsinogen into pepsin and killing bacteria,but it can damage the stomach wall if not for the mucus layer.
Therefore,mucus plays a crucial role in preventing gastric ulcers and protecting the stomach epithelium.

(C) The liver produces bile, which is stored in the gallbladder. Bile is released into the $duodenum$, which is the first part of the $small \ intestine$. This bile helps in the emulsification of fats, breaking down large fat globules into smaller droplets to facilitate digestion by enzymes.

(D) The iodine test is a chemical test used to detect the presence of starch in a sample.
When iodine solution ($I_2$ in $KI$) is added to a substance containing starch,it forms a starch-iodine complex,which results in a characteristic blue-black colour.
Since rice water turned blue-black upon the addition of iodine,it confirms the presence of starch in the rice water.
Therefore,the correct option is $D$.

(A) The process of digestion is completed in the $Small \, intestine$.
In the $Small \, intestine$, the food receives secretions from the liver (bile) and the pancreas (pancreatic juice).
The enzymes present in the pancreatic juice and the intestinal juice break down complex carbohydrates into glucose, proteins into amino acids, and fats into fatty acids and glycerol.
This is the final site where the digestion of all major nutrients is completed.

(B) Pancreatic juice contains several enzymes,including trypsin and lipase.
$1$. Trypsin is a proteolytic enzyme that breaks down proteins into peptides.
$2$. Lipase is an enzyme that acts on emulsified fats and breaks them down into fatty acids and glycerol.
Therefore,the correct function is that trypsin digests proteins and lipase digests emulsified fats.

(C) When we exhale,the air we breathe out contains a higher concentration of $CO_2$ compared to the air we inhale.
Lime water is a solution of calcium hydroxide,$Ca(OH)_2$.
When $CO_2$ is passed through lime water,it reacts to form calcium carbonate $(CaCO_3)$,which is insoluble in water and forms a white precipitate.
This reaction is represented as: $Ca(OH)_2(aq) + CO_2(g) \rightarrow CaCO_3(s) + H_2O(l)$.
The formation of this white precipitate of calcium carbonate makes the lime water appear milky.

(D) In yeast,the process of respiration is anaerobic (occurs in the absence of oxygen).
$1$. First,glucose $(C_6H_{12}O_6)$ is broken down into pyruvate in the cytoplasm of the cell,which is a common step for both aerobic and anaerobic respiration.
$2$. In the absence of oxygen,the pyruvate is further converted into ethanol $(C_2H_5OH)$ and carbon dioxide $(CO_2)$ within the cytoplasm of the yeast cell.
$3$. Therefore,the correct sequence is: Glucose $\xrightarrow{\text{cytoplasm}}$ Pyruvate $\xrightarrow{\text{cytoplasm}}$ Ethanol + Carbon dioxide.

(A) Aerobic respiration occurs in two main stages:
$1$. Glycolysis: This process takes place in the cytoplasm,where glucose ($6$-carbon molecule) is broken down into pyruvate ($3$-carbon molecule) and releases a small amount of energy.
$2$. Krebs Cycle and Electron Transport Chain: Pyruvate enters the mitochondria,where it is completely oxidized in the presence of oxygen to produce $CO_2$,$H_2O$,and a large amount of energy $(ATP)$.
Therefore,the correct sequence is: Glucose $\xrightarrow{\text{cytoplasm}}$ Pyruvate + Energy $\xrightarrow{\text{mitochondria}}$ $CO_2 + H_2O$ + Energy.

(B) Statement $(i)$ is false because during inhalation,the ribs move outward and the diaphragm moves downward (flattens) to increase the thoracic cavity volume.
Statement $(ii)$ is true because alveoli are the sites of gaseous exchange where oxygen diffuses into the blood and carbon dioxide diffuses out.
Statement $(iii)$ is false because haemoglobin has a much higher affinity for oxygen than for carbon dioxide.
Statement $(iv)$ is true because the millions of alveoli in the lungs significantly increase the surface area available for the exchange of gases.
Therefore,statements $(ii)$ and $(iv)$ are correct.

(C) During inhalation,the air enters the body through the nostrils.
From the nostrils,it passes into the pharynx,which is the common passage for air and food.
Then,the air moves into the larynx (voice box) and enters the trachea (windpipe).
The trachea branches into bronchi,which further divide into bronchioles and finally reach the alveoli,where gas exchange occurs.
Therefore,the correct sequence is: Nostrils $\to$ pharynx $\to$ larynx $\to$ trachea $\to$ alveoli.

(D) During the process of respiration,the exchange of gases ($O_2$ and $CO_2$) occurs in the alveoli of the lungs.
Alveoli are tiny,balloon-like structures present at the terminal ends of the bronchioles.
They provide a large surface area for the diffusion of gases between the air in the lungs and the blood in the surrounding capillaries.

(A) Statement $(i)$ is incorrect because the left atrium receives oxygenated blood from the lungs,not the body.
Statement $(ii)$ is correct because the left ventricle pumps oxygenated blood to the body,and the right ventricle pumps deoxygenated blood to the lungs.
Statement $(iii)$ is incorrect because the left atrium transfers blood to the left ventricle,not the right ventricle.
Statement $(iv)$ is correct because the right atrium receives deoxygenated blood from the body,and the left ventricle pumps oxygenated blood to the body.
Therefore,statements $(ii)$ and $(iv)$ are true.

(B) The heart contains specialized structures called valves (such as the tricuspid,bicuspid,and semilunar valves).
These valves act as one-way doors that open to allow blood to flow in the correct direction and close tightly to prevent the backflow of blood when the heart chambers (atria and ventricles) contract.
Therefore,valves are the primary structures responsible for ensuring unidirectional blood flow.

(C) Single circulation is a characteristic feature of fishes,where the heart receives only deoxygenated blood and pumps it to the gills for oxygenation,from where it passes directly to the rest of the body.
In the given options:
$A$: Labeo (fish),Chameleon (reptile),Salamander (amphibian).
$B$: Hyla (amphibian),Rana (amphibian),Draco (reptile).
$C$: Hippocampus (sea horse),Exocoetus (flying fish),Anabas (climbing perch). All these are bony fishes.
$D$: Whale (mammal),Dolphin (mammal),Turtle (reptile).
Therefore,option $C$ represents a group of organisms that all exhibit single circulation.

(D) In $Pisces$ (fishes),the heart is two-chambered,consisting of one atrium and one ventricle.
It pumps deoxygenated blood to the gills for oxygenation,and this oxygenated blood then goes directly to the rest of the body without returning to the heart.
Therefore,the heart in $Pisces$ only pumps deoxygenated blood.
In contrast,amphibians,reptiles,birds,and mammals have hearts that pump oxygenated blood to the body tissues.

(A) Arteries are the blood vessels that carry oxygenated blood away from the heart to various parts of the body (except the pulmonary artery).
Because the blood is pumped directly from the heart,it flows under high pressure.
To withstand this high pressure,arteries have thick,elastic walls.
Unlike veins,arteries do not have valves inside because the high pressure ensures the blood flows in only one direction.

(B) The kidneys contain many filtration units known as $nephrons$.
Each $nephron$ consists of a filtering component called the $glomerulus$ and a tubule.
$Nephrons$ are responsible for filtering the blood,reabsorbing essential substances,and excreting waste products in the form of urine.
Therefore,the correct option is $B$.

(C) During the process of photosynthesis,the light-dependent reaction involves the photolysis of water $(H_2O)$.
This process splits water molecules into hydrogen ions $(H^+)$,electrons $(e^-)$,and oxygen $(O_2)$.
The oxygen released is a byproduct of this water-splitting reaction,not from carbon dioxide $(CO_2)$.
Therefore,the correct source of oxygen liberated during photosynthesis is water.

(D) During cellular respiration,cells consume oxygen to produce energy and release $CO_2$ as a metabolic waste product.
As blood passes through the tissues,oxygen diffuses from the blood into the cells,while $CO_2$ produced by the cells diffuses into the blood.
Therefore,the blood leaving the tissues has a higher concentration of carbon dioxide compared to the blood entering the tissues.

(A) Life processes are the basic functions performed by living organisms to survive.
$1$. Organisms must repair and maintain their structure to prevent damage and breakdown,which requires energy.
$2$. Organisms grow with time as they synthesize new materials.
$3$. Energy is essential for all life processes,including metabolic activities.
$4$. The movement of molecules is a fundamental characteristic of life; molecules are constantly moving within and between cells to facilitate transport,signaling,and metabolic reactions.
Therefore,the statement that the movement of molecules does not take place among cells is incorrect.

(B) Autotrophs are organisms that produce their own food through the process of photosynthesis.
During photosynthesis,plants synthesize glucose,which is then converted into starch for storage.
Starch serves as the primary internal energy reserve in plants (autotrophs).
In contrast,animals (heterotrophs) store their energy in the form of glycogen.
Therefore,the correct answer is starch.

(C) Photosynthesis is the process by which green plants synthesize their food using carbon dioxide and water in the presence of sunlight and chlorophyll.
The balanced chemical equation for photosynthesis is:
$6 CO_{2} + 12 H_{2}O \xrightarrow[\text{Chlorophyll}]{\text{Sunlight}} C_{6}H_{12}O_{6} + 6 O_{2} + 6 H_{2}O$.
Option $C$ correctly represents this summary equation,including the essential requirements (sunlight and chlorophyll) and the products (glucose,oxygen,and water).

(D) Photosynthesis is a process by which green plants convert light energy into chemical energy.
The main events occurring during photosynthesis are:
$1$. Absorption of light energy by chlorophyll.
$2$. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
$3$. Reduction of carbon dioxide to carbohydrates.
Option $D$ is incorrect because carbon dioxide is reduced to carbohydrates,not oxidized to carbon dioxide. Oxidation of carbon to carbon dioxide is a process associated with respiration,not photosynthesis.

(A) The opening and closing of the stomatal pore is primarily regulated by the turgor pressure within the guard cells.
When water enters the guard cells through osmosis,they become turgid and swell,causing the stomatal pore to open.
Conversely,when water leaves the guard cells,they lose their turgidity and become flaccid,causing the stomatal pore to close.
Therefore,the movement of water into and out of the guard cells is the direct cause of stomatal movement.

(B) Plants require nitrogen for the synthesis of proteins and other compounds. Although nitrogen is abundant in the atmosphere,plants cannot absorb it directly in its gaseous form $(N_2)$.
Most plants absorb nitrogen from the soil in the form of inorganic compounds,primarily as nitrates $(NO_3^-)$ and nitrites $(NO_2^-)$.
Some plants can also absorb nitrogen in the form of urea or ammonium ions,but nitrates and nitrites are the most common forms absorbed by the majority of plants.
Therefore,the correct forms are $(ii)$ Nitrates and Nitrites and $(iii)$ Urea.

(C) The process of digestion begins in the mouth (buccal cavity).
Saliva secreted by the salivary glands contains the enzyme salivary amylase (also known as ptyalin).
This enzyme acts on starch present in the food and breaks it down into simpler sugars like maltose.
Therefore,salivary amylase is the first enzyme to mix with food in the digestive tract.

(D) Statement $(i)$ is correct: In yeast,during fermentation,pyruvate is converted into ethanol and $CO_2$ in the absence of oxygen.
Statement $(ii)$ is incorrect: Fermentation is an anaerobic process,not aerobic.
Statement $(iii)$ is incorrect: Fermentation occurs in the cytoplasm,not in the mitochondria.
Statement $(iv)$ is correct: Fermentation is a type of anaerobic respiration where glucose is incompletely oxidized without oxygen.
Therefore,statements $(i)$ and $(iv)$ are correct.

(A) During intense physical activity,such as cricket,the demand for energy in muscle cells increases significantly.
When the oxygen supply becomes insufficient to meet this demand,muscle cells switch to anaerobic respiration.
In this process,the pyruvate produced from glucose breakdown is converted into lactic acid instead of entering the aerobic pathway.
The accumulation of lactic acid in the muscle tissues causes muscle fatigue and painful cramps.

(B) The process of urine formation and excretion in the human body follows a specific pathway:
$1$. Urine is produced in the kidneys by the filtration of blood.
$2$. It then travels through the ureters,which are tubes connecting the kidneys to the urinary bladder.
$3$. The urinary bladder stores the urine until it is ready to be excreted.
$4$. Finally,the urine is expelled from the body through the urethra.
Therefore,the correct sequence is: Kidney $\to$ Ureters $\to$ Urinary bladder $\to$ Urethra.

(C) In human muscle cells,when there is a temporary deficiency of oxygen (anaerobic conditions),the pyruvic acid produced during glycolysis is reduced to lactic acid.
This process occurs in the cytoplasm of the cell.
Glycolysis itself takes place in the cytoplasm,and the subsequent reduction of pyruvate to lactate under anaerobic conditions also occurs in the cytoplasm,not in the mitochondria.

(N/A) Photosynthesis: The process by which green plants convert light energy into chemical energy stored in glucose.
$(b)$ Autotrophs: Organisms like plants that synthesize their own food using inorganic substances.
$(c)$ Chloroplast: The specialized cell organelle containing chlorophyll where photosynthesis takes place.
$(d)$ Guard Cells: Specialized cells that regulate the opening and closing of the stomatal pore.
$(e)$ Heterotrophs: Organisms that depend on other organisms for their food requirements.
$(f)$ Pepsin: $A$ digestive enzyme secreted by the gastric glands in the stomach that breaks down proteins into peptides.

(N/A) No,this statement is not entirely correct.
During the day,plants perform both photosynthesis and respiration. Since the rate of photosynthesis is significantly higher than the rate of respiration,the net result is the release of oxygen.
At night,photosynthesis stops because there is no sunlight,but respiration continues. Therefore,plants only release carbon dioxide at night.
Thus,while the statement is partially true regarding the net gas exchange,it is inaccurate to say plants 'only' give out oxygen during the day,as they are also respiring.

(N/A) The opening and closing of stomatal pores are regulated by the turgor pressure within the guard cells.
$1$. When water enters the guard cells through osmosis,they become turgid and swell.
$2$. Due to the specific orientation of cellulose microfibrils in the guard cell walls,the swelling causes the outer walls to bulge outwards,which pulls the inner walls apart,resulting in the opening of the stomatal pore.
$3$. Conversely,when water leaves the guard cells,they become flaccid and shrink.
$4$. This loss of turgor causes the inner walls to move closer together,thereby closing the stomatal pore.

(B) The plant kept in continuous light will live longer.
This is because,in the presence of light,the plant performs photosynthesis,which produces $O_2$ as a byproduct.
This $O_2$ is then utilized by the plant for its cellular respiration,allowing it to survive.
In contrast,the plant kept in the dark cannot perform photosynthesis and will quickly consume the limited oxygen available in the container,leading to its death.

(N/A) The release of $CO_2$ and the intake of $O_2$ indicates that either photosynthesis is not occurring or its rate is significantly lower than the rate of cellular respiration. Under normal daylight conditions,the rate of photosynthesis is much higher than the rate of respiration. Consequently,the $CO_2$ produced during respiration is consumed in the process of photosynthesis,meaning no $CO_2$ is released into the atmosphere.

(N/A) Fishes respire with the help of gills. Gills are richly supplied with blood capillaries and can readily absorb oxygen dissolved in water. Since fishes cannot absorb gaseous oxygen from the atmosphere,they die soon after they are taken out of water.

(N/A)

Autotroph	Heterotroph
$1$. Organisms that prepare their own food using simple inorganic substances.	$1$. Organisms that depend on other organisms for their food.
$2$. They contain chlorophyll to perform photosynthesis.	$2$. They lack chlorophyll and cannot perform photosynthesis.
$3$. Example: Green plants and some bacteria.	$3$. Example: Animals,fungi,and most bacteria.

(N/A) Yes,nutrition is a fundamental necessity for all living organisms for the following reasons:
$(a)$ Energy Provision: Food provides the energy required for various metabolic processes,such as respiration,circulation,and excretion,which are essential for maintaining life.
$(b)$ Growth and Repair: Nutrients are essential for the synthesis of new cellular components,facilitating the growth of the organism and the repair or replacement of damaged or worn-out cells and tissues.
$(c)$ Disease Resistance: Proper nutrition helps in strengthening the immune system,which is necessary to develop resistance against various diseases and infections.

(B) Green plants are the primary producers and the ultimate source of energy for all organisms in an ecosystem.
If all green plants disappear from the earth,the food chain will collapse.
Herbivores,which depend directly on plants for food,will die due to starvation.
Subsequently,carnivores,which depend on herbivores for food,will also die due to the lack of prey,leading to the extinction of life on earth.

(N/A) This plant will not remain healthy for a long time because:
$(a)$ It will not get oxygen for respiration.
$(b)$ It will not get carbon dioxide for photosynthesis.
$(c)$ The upward movement of water and minerals (transpiration pull) would be hampered due to the blockage of stomata,which prevents transpiration.

(N/A)

Aerobic respiration	Anaerobic respiration
$1.$ Oxygen is utilised for the breakdown of respiratory substrate.	$1.$ Oxygen is not required.
$2.$ It takes place in cytoplasm (glycolysis) and inside mitochondria (Krebs cycle).	$2.$ It takes place in cytoplasm only.
$3.$ End products are carbon dioxide and water.	$3.$ End products are lactic acid or ethanol and carbon dioxide.
$4.$ More energy is released.	$4.$ Less energy is released.

(A) The correct matches are as follows:
$(a)$ Phloem is responsible for the $(ii)$ Translocation of food in plants.
$(b)$ Nephron is the structural and functional unit of the kidney involved in $(i)$ Excretion.
$(c)$ Veins are blood vessels that carry $(iv)$ Deoxygenated blood towards the heart.
$(d)$ Platelets are blood cells that help in the $(iii)$ Clotting of blood.
Therefore,the correct sequence is $(a-ii, b-i, c-iv, d-iii)$.

(N/A)

Artery	Vein
$1.$ Have thick,elastic,muscular walls.	$1.$ Have thin,non-elastic walls.
$2.$ Lumen is narrow.	$2.$ Lumen is wide.
$3.$ Carry blood from the heart to all body parts.	$3.$ Carry blood from all body parts to the heart.
$4.$ Carry oxygenated blood (except pulmonary artery).	$4.$ Carry deoxygenated blood (except pulmonary vein).

(N/A) Leaves provide a large surface area for maximum light absorption.
$(b)$ Leaves are arranged in a way that minimizes overlapping to maximize light exposure.
$(c)$ The extensive network of veins enables quick transport of water and nutrients to and from the mesophyll cells.
$(d)$ Presence of numerous stomata allows for efficient gaseous exchange.
$(e)$ Chloroplasts are concentrated in the upper surface of leaves to capture maximum sunlight.

(N/A) The digestion of cellulose,a complex carbohydrate found in plant cell walls,requires a longer duration to break down.
Herbivores,which primarily consume grass and plant-based materials,possess a longer small intestine to provide sufficient time and surface area for the complete digestion and absorption of cellulose.
In contrast,carnivores consume meat,which is primarily composed of proteins and fats. These nutrients are easier and faster to digest than cellulose,which is why carnivores have a shorter small intestine.