10th Science - Book Back Answers - Biology Unit 12 - English Medium Guides

 

SSLC / 10th - Science - Book Back Answers - Biology Unit 12 - English Medium

Tamil Nadu Board 10th Standard  Science - Biology Unit 12: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 12 – Biology from the Tamil Nadu State Board 10th Standard  Science textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Biology Unit 12 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 10 students! Prepare well and aim for top scores. Thank you!

Topic: Plant Anatomy and Plant Physiology

I. Choose the correct Answer

1. Casparian strips are present in of the root.

(a) cortex

(b) pith

(c) pericycle

(d) endodermis

Answer Key:

(d) endodermis

2. The endarch condition is the characteristic feature of ______.

(a) root

(b) stem

(c) leaves

(d) flower.

Answer Key:

(b) stem

 

3. The xylem and phloem arranged side by side on same radius is called:

(a) radial

(b) amphivasal

(c) conjoint

(d) None of these

Answer Key:

(c) conjoint

4. Which is formed during anaerobic respiration:

(a) Carbohydrate

(b) Ethyl alcohol

(c) Acetyl CoA

(d) Pyruvate

Answer Key:

(b) Ethyl alcohol

 

5. Kreb’s cycle takes place in ______.

(a) chloroplast

(b) mitochondrial matrix

(с) stomata

(d) inner mitochondrial membrane.

Answer Key:

(b) mitochondrial matrix

 

6. Oxygen is produced at what point during photosynthesis?

(a) when ATP is converted to ADP

(b) when CO₂ is fixed

(c) when H₂O is splitted

(d) All of these

Answer Key:

(d) All of these

 

 

II. Fill in the blanks

1. Cortex lies between ……….
2. Xylem and phloem occur on the same radius constitute a vascular bundle called ………..
3. Glycolysis takes place in ………..
4. The source of O₂ liberated in photosynthesis is ……….
5. …….. is the ATP factory of the cells.
Answer Key:
1. epidermis and Pericycle
2. conjoint bundles
3. cytoplasm
4. splitting of Water molecules
5. Mitochondria

 

III. State whether the following statements are true or false. correct the statement if it is false.

1. Phloem tissue is involved in the transport of water in plants.
2. The waxy protective covering of a plant is called as the cuticle.
3. In monocot, stem cambium is present in between xylem and phloem.
4. Palisade parenchyma cells occur below the upper epidermis in the dicot root.
5. Mesophyll contains chlorophyll.
6. Anaerobic respiration produces more ATP than aerobic respiration.
Answer Key:
1. False – Phloem tissue is involved in the transport of food in plants.
2. True
3. False – In monocot stem cambium is absent.
4. True
5. True
6. False – Aerobic respiration produces more ATP than anaerobic respiration.

 

 

IV.  Match the following  

Column I		Column II
1	Amphicribal	i	Dracaena
2	Cambium	ii	Translocation of food
3	Amphivasal	iii	Fern
4	Xylem	iv	Secondary growth
5	Phloem	v	Conduction of water

 Answer Key:

Column I		Column II
1	Amphicribal	iii	Fern
2	Cambium	iv	Secondary growth
3	Amphivasal	i	Dracaena
4	Xylem	v	Conduction of water
5	Phloem	ii	Translocation of food

 

 

V. Answer in a sentence

1. What is the collateral vascular bundle?
Answer Key:
If xylem and phloem in a vascular bundle are arranged along the same radius with phloem towards the outside, such vascular bundle is called a collateral vascular bundle.
 
2. Where does the carbon that is used in photosynthesis come from?
Answer Key:
The carbon that is used in photosynthesis comes from CO₂ from the air.
 
3. What is the common step in aerobic and anaerobic pathway?
Answer Key:
Glycolysis is the common step in aerobic and anaerobic respiration.
 
4. Name the phenomenon by which carbohydrates are oxidized to release ethyl alcohol.
Answer Key:
Alcohol fermentation.

 

 

VI. Short answer question

1. Give an account on vascular bundle of dicot stem.
Answer Key:
Vascular bundles of dicot stem are conjoint (xylem and phloem lies in the same radius) collateral (xylem is the centre and phloem lies towards periphery) endarch (proto xylem in the centre, Meta xylem lies in the periphery) and open (cambium present in between xylem and phloem: They are arranged in the form of ring around the pith.

2. Write a short note on mesophyll.
Answer Key:
In Dicot leaf, the tissue present between the upper and lower epidermis is called mesophyll. It is differentiated into
1. Palisade Parenchyma: They are found below the epidermis and are elongated. They have a number of chloroplasts and can take part in photosynthesis. The cells do not have intercellular spaces.
2. Spongy Parenchyma: They are found below the palisade parenchyma tissue. Cells are spherical or oval and are irregularly arranged. Cells have intercellular spaces and help in gaseous exchange.
In monocot leaves, mesophyll is present between both upper and lower epidermal layer. The cells are irregularly arranged with intercellular spaces. Mesophyll cells contain chloroplasts, to take part in photosynthesis.

3. Draw and label the structure of oxysomes.
Answer Key:

 

4. Name the three basic – tissues systems in flowering plants.

Answer Key:
The three basic tissue system in flowering plants are:
• Dermal or epidermal tissue system.
• Ground tissue system.
• Vascular tissue system.

5. What is photosynthesis and where in a cell does it occur?
Answer Key:
Photosynthesis is a process by which autotrophic organisms (green plants, algae and chlorophyll containing bacteria) utilize the energy from sunlight to synthesize their own food. It occur in the chloroplast of the cell.

6. What is respiratory quotient?
Answer Key:
Respiratory quotient is the ratio of volume of carbon dioxide liberated and the volume of oxygen consumed during respiration. It is expressed as

$\mathbf{R}\mathbf{Q}\mathbf{=}\frac{\mathbf{V}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{m}\mathbf{e} \mathrm{of} {\mathrm{CO}}_{\mathbf{2}}\mathbf{l}\mathbf{i}\mathbf{b}\mathbf{e}\mathbf{r}\mathbf{a}\mathbf{t}\mathbf{e}\mathbf{d}}{\mathbf{V}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{m}\mathbf{e} \mathrm{of} {\mathrm{O}}_{\mathbf{2}}\mathbf{c}\mathbf{o}\mathbf{n}\mathbf{s}\mathbf{u}\mathbf{m}\mathbf{e}\mathbf{d}}$
 
7. Why should the light – dependent reaction occur before the light-independent reaction?
Answer Key:
In light – dependent photosynthesis, the photosynthetic pigment absorbs the light energy and convert it into chemical energy, ATP and NADPH₂. These products move out from grana to the stroma of the chloroplast for the light-independent reactions (Dark reaction or Biosynthetic pathway). During this reaction, CO₂ is reduced in the carbohydrates with the help of light generated ATP and NADPH₂. So the light-dependent reaction should occur before the light-independent reaction.
 
8. Write the reaction for photosynthesis.
Answer Key:
The overall reaction for photosynthesis.
$\mathbf{ \; \; \; \; \; 6}\mathbf{C}{\mathbf{O}}_{\mathbf{2}}\mathbf{+}\mathbf{12}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\underset{\mathbf{C}\mathbf{h}\mathbf{l}\mathbf{o}\mathbf{r}\mathbf{o}\mathbf{p}\mathbf{h}\mathbf{y}\mathbf{l}\mathbf{l}}{\overset{\mathrm{Light}}{\mathbf{\to }}}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{12}}{\mathbf{O}}_{\mathbf{6}}\mathbf{+}\mathbf{6}{\mathbf{H}}_{\mathbf{2}}\mathbf{+}\mathbf{6}{\mathbf{O}}_{\mathbf{2}}\mathbf{\uparrow }$
Carbon dioxide  water                Glucose   water   Oxygen

 

 

VII. Long answer questions

1. Differentiate the following:
(a) Monocot root and Dicot root
Answer Key:

Monocot Root	Dicot Root
Xylem is ploy arch.	Xylem is usually tetrarch.
Pitch is usually large at the centre.	Pitch is usually absent.
Conjuctive tissue is made up of sclerenchyma.	Conjuctive tissue is made up of parenchyma.
There is no secondary growth.	Secondary growth is generally present.

(b) Aerobic and Anaerobic respiration
Answer Key:

Aerobic Respiration	Anaerobic Respiration
It occurs in all living cells of higher organisms.	It occurs in yeast and some bacteria.
It requires oxygen for breaking the respiratory substrate.	Oxygen is not required for breaking the respiratory substrate.
The end products are CO2 and H2O.	The end products are alcohol and CO2.
Glucose molecules are completely oxidised.	Glucose molecules are partially broken down.

 
 
2. Describe and name three stages of cellular respiration that aerobic organisms use to obtain energy from glucose.
Answer Key:
The name and the three stages of cellular respiration.
• Glycolysis: (Glucose splitting): Glycolysis is the break down of one molecule of Glucose (6 Carbon) into two molecules of Pyruvic acid (3 Carbon). It takes place in the cytoplasm of the cell.
• Kreb’s cycle: This cycle occurs in the mitochondria matrix. At the end of Glycolysis, 2 molecules of pyruvic acid enter into mitochondria. The oxidation of pyruvic acid into CO₂ and H₂O takes place through this cycle. It is also called as Tricarboxylic Acid Cycle. (TCA)
• Electron transport chain: It is a system of Electron Transport Chain (ETC) located on the inner membrane of the mitochondria. NADH₂ and FADH₂ molecules formed during Glycolysis and Krebs cycle are oxidised to NAD+ and FAD+ to release the energy via electrons.
The electrons, as they move through the system, release energy which is trapped by ADP to synthesize ATP. This is called Oxidative Phosphorylation. During this process, oxygen which is the acceptor of electrons gets reduced to water.

3. How does the light dependent reaction differ from the light independent reaction?
What are the end product and reactants in each? Where does each reaction occur within the chioroplast?
Answer Key:

Light dependent reaction	Light independent reaction
The reaction involving pigments, solar energy and water that produce ATP and NADPH2 are called light dependent reaction.	The photosynthetic reaction in which CO2 is reduced to carbohydrates making use of ATP and NADPH2 generated by light independent reaction.
The end product is ATP and NADPH2.	The end product is carbohydrates.
This reaction takes place in Thylakoid membranes (grana) of the chloroplast.	It occurs in the stroma of the chloroplast.

VIII. HOTS questions

1. The reactions of photosynthesis make up a biochemical pathway.
(a) What are the reactants and products for both light and dark reactions.
Answer Key:
The reaction of photosynthesis can be grouped into two: Light and Dark reaction.
The reaction involving pigments, solar energy and water that produce ATP and NADPH₂ are called light reaction.
The photosynthetic reactions in which CO₂ is reduced to carbohydrates making use of ATP and NADPH₂ generated by light reaction are called dark reaction.
The overall reaction of photosynthesis can be written as follows:
$\mathbf{C}{\mathbf{O}}_{\mathbf{2}}\mathbf{+}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\underset{\mathbf{C}\mathbf{h}\mathbf{l}\mathbf{o}\mathbf{r}\mathbf{o}\mathbf{p}\mathbf{h}\mathbf{y}\mathbf{l}\mathbf{l}}{\overset{\mathbf{S}\mathbf{o}\mathbf{l}\mathbf{a}\mathbf{r}\mathbf{ }\mathbf{e}\mathbf{n}\mathbf{e}\mathbf{r}\mathbf{g}\mathbf{y}}{\mathbf{\to }}}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{12}}{\mathbf{O}}_{\mathbf{6}}\mathbf{+}{\mathbf{H}}_{\mathbf{2}}\mathbf{+}{\mathbf{O}}_{\mathbf{2}}\mathbf{\uparrow }$
(b) Explain how the biochemical pathway of photosynthesis recycles many of its own reactions and identify the recycled reactants.
Answer Key:
Light reaction use light to synthesize ATP and NADPH₂. The calvin cycle uses these reactants to produce sugar from CO₂ molecule.
This cycle then produce NAP + ADP + Pi which is used in light reaction with H₂O molecules to produce ATP and NADPH₂ again.
 
2. Where do the light-dependent reaction and the Calvin cycle occur in the chloroplast?
Answer Key:
The Light-dependent reaction occurs in the Thylakoid membranes (Grana) of the chloroplast. The Light independent reaction occurs in the stroma of the chloroplast.