15.7: Chapter 7 exercises - Biology

15.7: Chapter 7 exercises - Biology

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Multiple Choice

Which of the following is an organism that obtains its energy from the transfer of electrons originating from chemical compounds and its carbon from an inorganic source?

A. chemoautotroph
B. chemoheterotroph
C. photoheterotroph
D. photoautotroph

Which of the following molecules is reduced?

C. O2

Enzymes work by which of the following?

A. increasing the activation energy
B. reducing the activation energy
C.making exergonic reactions endergonic
D. making endergonic reactions exergonic

To which of the following does a competitive inhibitor most structurally resemble?

A. the active site
B. the allosteric site
C. the substrate
D. a coenzyme

Which of the following are organic molecules that help enzymes work correctly?

A. cofactors
B. coenzymes
C. holoenzymes
D. apoenzymes

Fill in the Blank

Processes in which cellular energy is used to make complex molecules from simpler ones are described as ________.

The loss of an electron from a molecule is called ________.

The part of an enzyme to which a substrate binds is called the ________.


Competitive inhibitors bind to allosteric sites.

Short Answer

In cells, can an oxidation reaction happen in the absence of a reduction reaction? Explain.

What is the function of molecules like NAD+/NADH and FAD/FADH2 in cells?

Multiple Choice

An operon of genes encoding enzymes in a biosynthetic pathway is likely to be which of the following?

A. inducible
B. repressible
C. constitutive
D. monocistronic

An operon encoding genes that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products is said to be which of the following?

A. repressible
B. inducible
C. activated

Which of the following conditions leads to maximal expression of the lac operon?

A. lactose present, glucose absent
B. lactose present, glucose present
C. lactose absent, glucose absent
D. lactose absent, glucose present

Which of the following is a type of regulation of gene expression unique to eukaryotes?

A. attenuation
B. use of alternate σ factor
C. chemical modification of histones
D. alarmones

Fill in the Blank

The DNA sequence, to which repressors may bind, that lies between the promoter and the first structural gene is called the ________.

The prevention of expression of operons encoding substrate use pathways for substrates other than glucose when glucose is present is called _______.

Short Answer

What are two ways that bacteria can influence the transcription of multiple different operons simultaneously in response to a particular environmental condition?

Critical Thinking

The following figure is from Monod’s original work on diauxic growth showing the growth of E. coli in the simultaneous presence of xylose and glucose as the only carbon sources. Explain what is happening at points A–D with respect to the carbon source being used for growth, and explain whether the xylose-use operon is being expressed (and why). Note that expression of the enzymes required for xylose use is regulated in a manner similar to the expression of the enzymes required for lactose use.

Multiple Choice

During which of the following is ATP not made by substrate-level phosphorylation?

A. Embden-Meyerhof pathway
B. Transition reaction
C. Krebs cycle
D. Entner-Doudoroff pathway

Which of the following products is made during Embden-Meyerhof glycolysis?

B. pyruvate
C. CO2
D. two-carbon acetyl

During the catabolism of glucose, which of the following is produced only in the Krebs cycle?


Which of the following is not a name for the cycle resulting in the conversion of a two-carbon acetyl to one ATP, two CO2, one FADH2, and three NADH molecules?

A. Krebs cycle
B. tricarboxylic acid cycle
C. Calvin cycle
D. citric acid cycle


Glycolysis requires oxygen or another inorganic final electron acceptor to proceed.

Fill in the Blank

Per turn of the Krebs cycle, one acetyl is oxidized, forming ____ CO2, ____ ATP, ____ NADH, and ____ FADH2molecules.

Most commonly, glycolysis occurs by the ________ pathway.

Short Answer

What is substrate-level phosphorylation? When does it occur during the breakdown of glucose to CO2?

Why is the Krebs cycle important in both catabolism and anabolism?

Critical Thinking

What would be the consequences to a cell of having a mutation that knocks out coenzyme A synthesis?

Multiple Choice

Which is the location of electron transports systems in prokaryotes?

A. the outer mitochondrial membrane
B. the cytoplasm
C. the inner mitochondrial membrane
D. the cytoplasmic membrane

Which is the source of the energy used to make ATP by oxidative phosphorylation?

A. oxygen
B. high-energy phosphate bonds
C. the proton motive force
D. Pi

A cell might perform anaerobic respiration for which of the following reasons?

A. It lacks glucose for degradation.
B. It lacks the transition reaction to convert pyruvate to acetyl-CoA.
C. It lacks Krebs cycle enzymes for processing acetyl-CoA to CO2.
D. It lacks a cytochrome oxidase for passing electrons to oxygen.

In prokaryotes, which of the following is true?

A. As electrons are transferred through an ETS, H+ is pumped out of the cell.
B. As electrons are transferred through an ETS, H+ is pumped into the cell.
C. As protons are transferred through an ETS, electrons are pumped out of the cell.
D. As protons are transferred through an ETS, electrons are pumped into the cell.

Which of the following is not an electron carrier within an electron transport system?

A. flavoprotein
B. ATP synthase
C. ubiquinone
D. cytochrome oxidase

Fill in the Blank

The final ETS complex used in aerobic respiration that transfers energy-depleted electrons to oxygen to form H2O is called ________.

The passage of hydrogen ions through ________ down their electrochemical gradient harnesses the energy needed for ATP synthesis by oxidative phosphorylation.


All organisms that use aerobic cellular respiration have cytochrome oxidase.

Short Answer

What is the relationship between chemiosmosis and the proton motive force?

How does oxidative phosphorylation differ from substrate-level phosphorylation?

How does the location of ATP synthase differ between prokaryotes and eukaryotes? Where do protons accumulate as a result of the ETS in each cell type?

Multiple Choice

Which of the following is the purpose of fermentation?

A. to make ATP
B. to make carbon molecule intermediates for anabolism
C. to make NADH
D. to make NAD+

Which molecule typically serves as the final electron acceptor during fermentation?

C. pyruvate
D. CO2

Which fermentation product is important for making bread rise?

A. ethanol
B. CO2
C. lactic acid
D. hydrogen gas

Which of the following is not a commercially important fermentation product?

A. butanol
D. penicillin

Fill in the Blank

The microbe responsible for ethanol fermentation for the purpose of producing alcoholic beverages is ________.

________ results in the production of a mixture of fermentation products, including lactic acid, ethanol and/or acetic acid, and CO2.

Fermenting organisms make ATP through the process of ________.


Match the fermentation pathway with the correct commercial product it is used to produce:

___acetone-butanol-ethanol fermentationa. bread
___alcohol fermentationb. pharmaceuticals
___lactic acid fermentationc. Swiss cheese
___mixed acid fermentationd. yogurt
___propionic acid fermentatione. industrial solvents

Short Answer

Why are some microbes, including Streptococcus spp., unable to perform aerobic respiration, even in the presence of oxygen?

How can fermentation be used to differentiate various types of microbes?

Critical Thinking

The bacterium E. coli is capable of performing aerobic respiration, anaerobic respiration, and fermentation. When would it perform each process and why? How is ATP made in each case?

Multiple Choice

Which of the following molecules is not produced during the breakdown of phospholipids?

A. glucose
B. glycerol
C. acetyl groups
D. fatty acids

Caseinase is which type of enzyme?

A. phospholipase
B. lipase
C. extracellular protease
D. intracellular protease

Which of the following is the first step in triglyceride degradation?

A. removal of fatty acids
B. β-oxidation
C. breakage of fused rings
D. formation of smaller peptides

Fill in the Blank

The process by which two-carbon units are sequentially removed from fatty acids, producing acetyl-CoA, FADH2, and NADH is called ________.

The NADH and FADH2 produced during β-oxidation are used to make ________.

________ is a type of medium used to detect the production of an extracellular protease called caseinase.

Short Answer

How are the products of lipid and protein degradation connected to glucose metabolism pathways?

What is the general strategy used by microbes for the degradation of macromolecules?

Critical Thinking

Do you think that β-oxidation can occur in an organism incapable of cellular respiration? Why or why not?

Multiple Choice

During the light-dependent reactions, which molecule loses an electron?

A. a light-harvesting pigment molecule
B. a reaction center pigment molecule
C. 3-phosphoglycerate

In prokaryotes, in which direction are hydrogen ions pumped by the electron transport system of photosynthetic membranes?

A. to the outside of the plasma membrane
B. to the inside (cytoplasm) of the cell
C. to the stroma
D. to the intermembrane space of the chloroplast

Which of the following does not occur during cyclic photophosphorylation in cyanobacteria?

A. electron transport through an ETS
B. photosystem I use
C. ATP synthesis
D. NADPH formation

Which are two products of the light-dependent reactions are ________.

A. glucose and NADPH
C. glyceraldehyde 3-phosphate and CO2
D. glucose and oxygen


Photosynthesis always results in the formation of oxygen.

Fill in the Blank

The enzyme responsible for CO2 fixation during the Calvin cycle is called ________.

The types of pigment molecules found in plants, algae, and cyanobacteria are ________ and ________.

Short Answer

Why would an organism perform cyclic phosphorylation instead of noncyclic phosphorylation?

What is the function of photosynthetic pigments in the light-harvesting complex?

Critical Thinking

Is life dependent on the carbon fixation that occurs during the light-independent reactions of photosynthesis? Explain.

NCERT Solutions for Class 11 Biology Chapter 7 Free PDF Download

NCERT Solutions for Class 11 Biology Chapter 7- Structural Organisation in Animals allows the students to explore the world of animals and their internal and external features. After going through our easy and simple solutions made by our subject expert teachers, students will confidently identify the subject better and will be able to perform well in this subject.

Class 11 comes with new challenges that one is not prepared for. In other words, it poses quite a number of difficulties in understanding the material. You need to prepare yourself accordingly to become better at it. Our NCERT Solutions for Class 11 Biology Chapter 7 will help with it and that too very efficiently.

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CBSE Class 11 Biology Chapter 7 Structural Organisation in Animals NCERT Solutions

NCERT Solutions for Class 11 Biology Chapter 7 teaches the students about the structural organization of animals. Subsequently, it discusses the different types of tissues present in various animals. After this chapter, students will be able to understand better the functioning of the animals and their bodily functions. In other words, it will enable them to comprehend the four types of tissues found in animals and their importance in an easy way. Therefore, our NCERT solutions will guide you effectively when learning about this chapter.

Sub topics covered under NCERT Solutions for Class 11 Biology Chapter 7

7.1 Animal Tissues-

In this section, students will learn about the types of animal tissues. Furthermore, it divides into four parts which are:

  • 7.1.1 Epithelial Tissue- This sub-section tells about the characteristics of epithelial tissue.
  • 7.1.2 Connective Tissue- Here, it discusses the most abundant and widely distributed tissues which are the connective tissue.
  • 7.1.3 Muscle Tissue- Students will learn about muscle tissue here and its types. In addition, it explains the skeletal muscle, smooth muscle, and cardiac muscle tissue.
  • 7.1.4 Neural Tissue- This section explains the functioning of the neural tissue and its importance.

7.2 Organ and Organ System-

The sub-part over here throws light on the organs of the bodies of living beings. It further explains the various organ systems of the following animals.

7.3 Earthworm-

Students will learn in brief about earthworms and their characteristics. It further divides into categories of:

  • 7.3.1 Morphology- The morphology of an earthworm is given here. Moreover, we understand the different body parts of the earthworm.
  • 7.3.2 Anatomy– The anatomy of an earthworm i.e. the internal organs will be discussed here.

7.4 Cockroach-

Up next, students will learn all about cockroaches. They will see furthermore study about their morphology and anatomy.

  • 7.4.1 Morphology- Over here, one will learn about the external features of a cockroach’s body
  • 7.4.2 Anatomy- This section will help students analyse clearly how the organs of a cockroach’s bodywork.

7.5 Frog-

Over here, you will get the chance to learn about this amphibian which lives on both land and in water. Furthermore, you will understand their external and internal features.

  • 7.5.1 Morphology- After this morphology, you will be able to easily understand the external features of a frog’s body.
  • 7.5.2 Anatomy- This anatomy will help you learn about their internal organs and how they function with them.

Summary- After this chapter, you will be given a summarized version of the topic. This will help you revise the chapter briefly and understand all the content in a short way.

You can download NCERT Solutions for Class 11 Biology Chapter 7 PDF by clicking on the button below.

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NCERT Solutions For Class 11 Biology Chapter 7: Structural Organisation In Animals

We have provided here the CBSE NCERT solutions for Class 11 Biology Chapter 7 along with a direct link to the NCERT solutions for Class 11 Biology Chapter 7 PDF download free to help the students prepare well for the exam. Finding the right books and solutions usually turns into a grueling task with a plethora of links available on the Internet. If you have also been struggling with the same issue then look no further. The NCERT Solutions for Class 11 Biology Chapter 7 PDF can easily be downloaded from the embibe platform who are looking for authentic textbooks to download.

Before getting into the detailed 11th Biology Chapter 7 solutions, let’s look at the topics and sub-topics included in the chapter:

7.1Animal Tissues
7.1.1Epithelial Tissue
7.1.2Connective Tissue
7.1.3Muscle Tissue
7.1.4Neural Tissue
7.2Organ and Organ System

NCERT Solutions For Class 11 Biology Chapter 7 – Chapter Description – Structural Organisation In Animals

The chapter – Structural Organisation in Animals mainly deals with the gross structural features, both external and internal, of animals. Here in this chapter, the structural organization of and animals, including the structural basis of physiological or behavioral phenomena is described. Students will get to know how tissues form organs and organ systems. A clear understanding of epithelial tissues, connective tissue, muscle tissue, and neural tissue is provided in this unit. This is a medium weightage chapter. Every year around 8 to 10 questions are asked from this chapter.

How To Prepare For The Chapter – Structural Organisation In Animals?

Biology is a subject where you need to memorize a lot of information. For this, you need to understand the concepts and practice a lot. A strong foundation from the beginning will help you. After solving the exercise questions, students can solve Class 11 Biology Chapter 7 practice questions and take Structural Organizations in Animals mock test to know where they stand and in which areas they need to improve. Students can download CBSE 11th Biology Chapter 7 Solutions PDF from this article.

Important Questions For NCERT Solutions For Class 11 Biology Chapter 7

Some of the important questions from CBSE Class 11 Biology Chapter 7 are as under:

  1. Name the tissue which contains Have risen canals?
  2. Mention two special properties of nervous tissues.
  3. Name the large cells present in adipose tissue.
  4. Name the cells responsible for clotting of blood.
  5. What are exocrine glands?
  1. What are the two types of fibres of connective tissues? Distinguish between the two.
  2. Give the characteristic of epithelial tissues.
  3. What do you mean by haemopoiesis?
  4. Differentiate between blood and lymph?
  5. What are nissl’s granules? Where are they found?
  1. Give three differences between frogs and toads?
  2. What do you understand by open type of circulatory system?
  3. What are the cellular components of blood?
  4. How do erythrocytes transport oxygen & carbon dioxide in the blood?
  5. Describe briefly the structure of voluntary muscles.

While preparing for this chapter – NCERT Solutions For Class 11 Biology Chapter 7 students must be aware of the important questions and the weightage of the chapter. As this chapter is of medium weightage students need not invest much of their time here. Go through the previous year papers and solve Class 11 Biology Chapter 7 practice questions and take Structural Organizations in Animals mock test to know where you need to improve.

Exercises 15.3

False. It is true for line integrals over scalar fields, though.

We can conclude that F → is conservative.

11 / 6 . (One parametrization for C is r → ⁢ ( t ) = ⟨ 3 ⁢ t , t ⟩ on 0 ≤ t ≤ 1 .)

0 . (One parametrization for C is r → ⁢ ( t ) = ⟨ cos ⁡ t , sin ⁡ t ⟩ on 0 ≤ t ≤ π .)

12 . (One parametrization for C is r → ⁢ ( t ) = ⟨ 1 , 2 , 3 ⟩ + t ⁢ ⟨ 3 , 1 , - 1 ⟩ on 0 ≤ t ≤ 1 .)

5 / 6 joules. (One parametrization for C is r → ⁢ ( t ) = ⟨ t , t ⟩ on 0 ≤ t ≤ 1 .)

Yes. f ⁢ ( x , y , z ) = x 2 / x + x ⁢ y + z 3 / 3 .

Since F → is conservative, it is the gradient of some potential function. That is, ∇ ⁡ f = ⟨ f x , f y , f z ⟩ = F → = ⟨ M , N , P ⟩ . In particular, M = f x , N = f y and P = f z .

Note that curl ⁡ F → = ⟨ P y - N z , M z - P x , N x - M y ⟩ = ⟨ f z ⁢ y - f y ⁢ z , f x ⁢ z - f z ⁢ x , f y ⁢ x - f x ⁢ y ⟩ , which, by Theorem 13.3.1 , is ⟨ 0 , 0 , 0 ⟩ .

(b) No. Hint: Think of how f is defined.

NCERT Solutions For Class 12 Biology Chapter 7: Evolution

Our experienced faculty always emphasizes that students must know the topics covered in the chapter to make the learning process easier.

Section NameSection Name
7.1Origin of Life
7.2Evolution of Life Forms – A Theory
7.3What is the Evidence for Evolution?
7.4What is Adaptive Radiation?
7.5Biological Evolution
7.6Mechanism of Evolution
7.7Hardy – Weinberg Principle
7.8A Brief Account of Evolution
7.9Origin and Evolution of Man

NCERT Solutions For Class 12 Biology Chapter 7 PDF Download – Evolution

Students can check the NCERT Solutions for Class 12 Biology Chapter 7 here:

Avail of the NCERT Solutions for Class 12 Biology Chapter 7 here. Besides that, you can also download the Evolution Class 12 Biology free PDF to study offline.

CBSE Class 12 Biology Chapter 7 – Chapter Description

Evolution can be called the study of the origin and development of life forms on earth. Have you ever questioned how did humans appear on earth? How do different kinds of organisms exist in different habitats, and how was the origin of life? The concept of evolution scientifically gives answers to these questions . Many theories have been proposed regarding the origin of life.

It is said that the first non-cellular forms of life could have originated 3 billion years back. These could be molecules such as RNA, Protein, Polysaccharides, etc. The first organisms could be single-cell organisms that lived in a water medium. These single-cell organisms eventually evolved into larger organisms over millions of years.

In this chapter, you will learn more about evolution. Darwinian ideas of organic evolution by natural selection, other phenomenon such as habitat fragmentation and genetic drift are also discussed. Besides, comparative anatomy, fossils, and comparative biochemistry provide evidence for evolution apart from the stories of the evolution of individual species. Most interestingly, we will also study the evolution of human beings with different stages of development.

How To Use NCERT Solutions For Class 12 Biology?

  • i) Study the chapter topic wise and understand the various concepts.
  • ii) First, try to solve the questions by yourself and then look at the solutions.
  • iii) Use them as a reference guide while revising the chapter.
  • iv) If you get stuck at any question, you can check the step by step solution from the PDF.

We have now provided you with the NCERT Solutions for Class 12 Biology Chapter 7 – Evolution. You can skillfully use them for your benefit. Along with providing NCERT solutions, Embibe also helps you in preparing for medical entrance tests for free. In addition, CIt provides free CBSE Class 12 Biology Chapter 7 practice questions and Evolution mock tests. Make the best use of these resources and master the chapter.

FAQs Related to NCERT Solutions for Class 12 Biology Chapter 7

A. Adaptive radiation is the relatively fast evolution of many species from a single common ancestor. Adaptive radiation generally occurs when an organism enters a new area, and different traits affect its survival. An example of adaptive radiation is the development of mammals after the extinction of dinosaurs.

A. A. List of all the exercises of NCERT Solutions for Class 12 Biology Chapter 7 PDF is given below:
Exercise 7.1: Origin of Life
Exercise 7.2: Evolution of Life Forms – A Theory
Exercise 7.3: What is the Evidence for Evolution?
Exercise 7.4: What is Adaptive Radiation?
Exercise 7.5: Biological Evolution
Exercise 7.6: Mechanism of Evolution
Exercise 7.7: Hardy – Weinberg Principle
Exercise 7.8: A Brief Account of Evolution
Exercise 7.9: Origin and Evolution of Man

A. There are four mechanisms of evolution – natural selection, mutation, gene flow, and genetic drift. All these mechanisms help a population evolve and change its genetic makeup over generations.

A. On this Embibe Page, candidates can download the PDF of NCERT Solutions for Class 12 Biology Chapter 7 Evolution.

A. Modern humans originated in Africa within the past 200,000 years and evolved from their most likely recent common ancestor, Homo erectus, which means ‘upright man’ in Latin. Homo erectus is an extinct species of human that lived between 1.9 million and 135,000 years ago.

We hope this article helps you. If you have any questions, feel free to post them in the comment section below. We will be happy to help you.

Please go throrugh the list of chapters and click on the desired chapters.

NCERT Solutions for Class 7 Science provide an Up-to-Date and comprehensive coverage of Science syllabus specified by Central Board of Secondary Education (CBSE). Class 7 Science NCERT Solutions are especially written for students who wish to score an excellent grade in their examination.

All topics of CBSE Class 7 Science are comprehensively dealt with to give students a firm grip on the subject. Explanations of concepts & principles are concise and written in a clear language. Exercises have been clearly graded to aid students in progressing within, as well as moving up each level. Unsolved questions are provided at appropriate places & intervals to enable students to recapitulate what they have learn. This solutions serves to outline the CBSE Class 7 Science knowledge & skills as prescribed in the latest syllabus.

NCERT Science Class 7 Solutions has following features:

Here is the list of chapters with brief introductions:

Chapter 1 Nutrition in Plants

This chapter deals with the mode of nutrition and how living organisms overcome their need for food and nutrition.

Chapter 2 Nutrition in Animals

This chapter deals with how the animals get their food from plants- either eating the plants directly or eating those animals which feed on plants for their nutrition.

Chapter 3 Fiber to Fabric

This chapter deals with different types of fibers like silk, wool, how these materials are produced and different methods of processing.

Chapter 4 Heat

This chapter deals with questions regarding heat and measurement of heat. This chapter consists of a special type of questions for easier understanding.

Chapter 5 Acids, Bases, and Salts

This chapter deals with different types of acids, bases and the combination of both results in the formation of salt. The concept of indicators is learned here.

Chapter 6 Physical and Chemical changes

This chapter describes two types of changes- physical changes( in which only the physical appearance of substance changes ) and chemical changes(in which the internal structure gets changed)

Chapter 7 Weather, Climate and Adaptations of Animals to Climate

This chapter studies weather and climate. It outlines the difference between weather and climate and the methods to cope up with different climatic variations(adaptation).

Chapter 8 Winds, storms, and cyclones

This chapter deals with the science behind the natural calamities like floods, storms, cyclones, etc. Why, how, and when they are formed are a few questions answered in this chapter.

Chapter 9 Soil

This chapter deals with soil its nature and properties in detail in this chapter.

Chapter 10 Respiration in Organisms

This chapter deals with the topic of respiration as a vital biological process and breathing.Why do organisms respire, how does respiration occur, respiration underwater are some of the topics discussed in this chapter.

Chapter 11 Transportation in Plants and Animals

This chapter deals with the transport of different substance within plants and animals. It also deals with the circulatory system in human beings. Also, different components of circulation like blood, blood vessel, and heart are discussed in this chapter.

Chapter 12 Reproduction in Plants

This chapter introduces the reproduction in plants. Different modes of reproduction in plants are further discussed in this chapter.

Chapter 13 Motion and Time

This chapter of physics deals with the fundamentals of speed incuding types and calculation of speed and motion.

Chapter 14 Electric Current and its effects

It deals with the basics of electric current, heating and magnetic effect of current and its application.

Chapter 15 Light

This chapter deals with formation, nature and different phenomenon of light.Daily life examples, images, and activities make this chapter interesting to learn and understand.

Chapter 16 Water- A Precious Resource

This chapter addresses one of the most important necessity of life on earth -water.different forms of water, underground water, distribution of water, water management, etc, are topics discussed in this chapter.

Chapter 17 Forests Our Lifeline

This chapter brings to notice the condition of forests in our country,their importance and effects of their depletion on the environment and mankind.

Chapter 18 Wastewater Story

It deals with water as lifeline resource for life on earth.

The solutions are guaranteed to be error-free and easily comprehensible. The students are advised to refer to these authentic solutions against the multiple refresher books. The NCERT textbooks are prescribed by CBSE, and hence form the most authentic source of knowledge in the school syllabus. NCERT solutions will help in the following manner:

  1. Authentic Homework Guide
  2. The base for the preparation of competitive exams like JEE and NEET
  3. Strengthening basic concepts of subjects
  4. Error-free solutions
  5. Extra problems to build upon the basic concepts

In the end we can say that with adequate preparation through this book, students will gain a thorough understanding & mastery of the subject. This NCERT Solutions for Class 7 Science will boost students confidence in the examinations.

NCERT Solutions

FAQs on NCERT Solutions for Class 7 Science

1. Which Science Book is Best for CBSE Class 7?

NCERT is more than enough for a Class 7th Student. Try covering the concepts thoroughly from the NCERT Textbooks and use them as a reference while preparing.

2. Where can I get free NCERT Solutions for Class 7 Science?

You can get the NCERT Solutions for Class 7 Science by referring to the direct links available on our site. Use them as a reference and aid your preparation.

3. How to study for the Class 7 Science Exam?

You can study for the Class 7 Science Exam by referring to NCERT Solutions. In addition, you can refer to the Class 7 Science Syllabus and Previous Papers to have a grip on the subject.

4. Where can I download NCERT Class 7 Science Solutions?

Candidates can download the NCERT Class 7 Science Solutions from our page. Use them whenever you feel like preparing and get to know the concepts better.

5. How many Chapters are there in Class 7 Science Book?

You will have 18 Chapters in the Class 7 Science Book. NCERT Solutions for Class 7 Science acts as the best resource to study all the Chapters easily. Download the Chapter of your choice and prepare as per your wish.

6. How to use NCERT Solutions for scoring more marks in the Class 7 Science Exam?

Download the NCERT Solutions prevailing on our page and prepare the chapter you wish for. Click on the link available and you will be directed to a new page that contains all the solutions for Class 7 Science. Prepare them and score well in the exam.

Chapter Summary

ATP functions as the energy currency for cells. It allows the cell to store energy briefly and transport it within the cell to support endergonic chemical reactions. The structure of ATP is that of an RNA nucleotide with three phosphates attached. As ATP is used for energy, a phosphate group or two are detached, and either ADP or AMP is produced. Energy derived from glucose catabolism is used to convert ADP into ATP. When ATP is used in a reaction, the third phosphate is temporarily attached to a substrate in a process called phosphorylation. The two processes of ATP regeneration that are used in conjunction with glucose catabolism are substrate-level phosphorylation and oxidative phosphorylation through the process of chemiosmosis.

7.2 Glycolysis

Glycolysis is the first pathway used in the breakdown of glucose to extract energy. It was probably one of the earliest metabolic pathways to evolve and is used by nearly all of the organisms on earth. Glycolysis consists of two parts: The first part prepares the six-carbon ring of glucose for cleavage into two three-carbon sugars. ATP is invested in the process during this half to energize the separation. The second half of glycolysis extracts ATP and high-energy electrons from hydrogen atoms and attaches them to NAD + . Two ATP molecules are invested in the first half and four ATP molecules are formed by substrate phosphorylation during the second half. This produces a net gain of two ATP and two NADH molecules for the cell.

7.3 Oxidation of Pyruvate and the Citric Acid Cycle

In the presence of oxygen, pyruvate is transformed into an acetyl group attached to a carrier molecule of coenzyme A. The resulting acetyl CoA can enter several pathways, but most often, the acetyl group is delivered to the citric acid cycle for further catabolism. During the conversion of pyruvate into the acetyl group, a molecule of carbon dioxide and two high-energy electrons are removed. The carbon dioxide accounts for two (conversion of two pyruvate molecules) of the six carbons of the original glucose molecule. The electrons are picked up by NAD + , and the NADH carries the electrons to a later pathway for ATP production. At this point, the glucose molecule that originally entered cellular respiration has been completely oxidized. Chemical potential energy stored within the glucose molecule has been transferred to electron carriers or has been used to synthesize a few ATPs.

The citric acid cycle is a series of redox and decarboxylation reactions that remove high-energy electrons and carbon dioxide. The electrons temporarily stored in molecules of NADH and FADH2 are used to generate ATP in a subsequent pathway. One molecule of either GTP or ATP is produced by substrate-level phosphorylation on each turn of the cycle. There is no comparison of the cyclic pathway with a linear one.

7.4 Oxidative Phosphorylation

The electron transport chain is the portion of aerobic respiration that uses free oxygen as the final electron acceptor of the electrons removed from the intermediate compounds in glucose catabolism. The electron transport chain is composed of four large, multiprotein complexes embedded in the inner mitochondrial membrane and two small diffusible electron carriers shuttling electrons between them. The electrons are passed through a series of redox reactions, with a small amount of free energy used at three points to transport hydrogen ions across a membrane. This process contributes to the gradient used in chemiosmosis. The electrons passing through the electron transport chain gradually lose energy, High-energy electrons donated to the chain by either NADH or FADH2 complete the chain, as low-energy electrons reduce oxygen molecules and form water. The level of free energy of the electrons drops from about 60 kcal/mol in NADH or 45 kcal/mol in FADH2 to about 0 kcal/mol in water. The end products of the electron transport chain are water and ATP. A number of intermediate compounds of the citric acid cycle can be diverted into the anabolism of other biochemical molecules, such as nonessential amino acids, sugars, and lipids. These same molecules can serve as energy sources for the glucose pathways.

7.5 Metabolism without Oxygen

If NADH cannot be oxidized through aerobic respiration, another electron acceptor is used. Most organisms will use some form of fermentation to accomplish the regeneration of NAD + , ensuring the continuation of glycolysis. The regeneration of NAD + in fermentation is not accompanied by ATP production therefore, the potential of NADH to produce ATP using an electron transport chain is not utilized.

7.6 Connections of Carbohydrate, Protein, and Lipid Metabolic Pathways

The breakdown and synthesis of carbohydrates, proteins, and lipids connect with the pathways of glucose catabolism. The simple sugars are galactose, fructose, glycogen, and pentose. These are catabolized during glycolysis. The amino acids from proteins connect with glucose catabolism through pyruvate, acetyl CoA, and components of the citric acid cycle. Cholesterol synthesis starts with acetyl groups, and the components of triglycerides come from glycerol-3-phosphate from glycolysis and acetyl groups produced in the mitochondria from pyruvate.

7.7 Regulation of Cellular Respiration

Cellular respiration is controlled by a variety of means. The entry of glucose into a cell is controlled by the transport proteins that aid glucose passage through the cell membrane. Most of the control of the respiration processes is accomplished through the control of specific enzymes in the pathways. This is a type of negative feedback, turning the enzymes off. The enzymes respond most often to the levels of the available nucleosides ATP, ADP, AMP, NAD + , and FAD. Other intermediates of the pathway also affect certain enzymes in the systems.

Pearson Baccalaureate Biology Higher Level 2nd edition print and ebook bundle for the IB Diploma

DNA interactive - genetics animation of Thomas Hunt Morgan’s Drosophila experiments at his Fly Room at Columbia University. Includes examples of Punnett squares showing sex linkage. - This link is currently unavailable
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Contributions to the genetics of Drosophila melanogaster full text - This link is currently unavailable
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Images of fruit fly mutations from the Exploratorium. - This link is currently unavailable
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Basics of allergies & relation to histamine - This link is currently unavailable
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How a grasshopper jumps an amazing distance - This link is currently unavailable
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Muscle anatomy / physiology site - This link is currently unavailable
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Excellent muscle / skeletal diagrams - This link is currently unavailable
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Animation of muscle contraction - This link is currently unavailable
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Overview of excretion in various animals - This link is currently unavailable
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Internal vs. external fertilization - This link is currently unavailable
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Placental hormones - This link is currently unavailable
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This interactive website shows the typical model organisms used in biological research. - This link is currently unavailable
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To read more about the work with spinal cord injuries and see the work of Professor Courtine go to his webpage. - This link is currently unavailable
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Brain plasticity: How learning changes your brain - This link is currently unavailable
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Watch the video: Chapter 7 Membrane Structure and Function (July 2022).


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