UPSC CSE Complete Practice Test - 4 - UPSC MCQ

• Permanent wilting point (PWP) or wilting point (WP) is defined as the minimum amount of water in the soil that the plant requires not to wilt. If the soil water content decreases to this or any lower point a plant wilts and can no longer recover its turgidity when placed in a saturated atmosphere for 12 hours. Turgidity is the state of being turgid or swollen, especially due to high fluid content. Turgidity is essential in plant cells to make them keep standing upright. Plant cells that lose much water have less turgor pressure and tend to become flaccid.
• The matric potential at this soil moisture condition is commonly estimated at -15 bar. Most agricultural plants will generally show signs of wilting long before this moisture potential or water content is reached (more typically at around -2 to -5 bars) because the rate of water movement to the roots decreases and the stomata tend to lose their turgor pressure and begin to restrict transpiration.
• This water is strongly retained and trapped in the smaller pores and does not readily flow. The volumetric soil moisture content at the wilting point will have dropped to around 5 to 10% for sandy soils, 10 to 15% in loam soils, and 15 to 20% in clay soils.
• Hence option (c) is the correct answer.

Statement 2 is incorrect.

Koraput Kala Jeera Rice

• The black-coloured rice variety, also known as the ‘Prince of Rice’, is famous for its aroma, taste, texture and nutritional value. Tribal farmers of the Koraput region have preserved the rice variety for around 1,000 years. As the rice grains resemble cumin seeds, it is also called Kala Jeera. Consumption of the rice variety helps in increasing haemoglobin levels and improves metabolism in the body.
• The farmers and producers of Koraput Kala Jeera rice have followed the traditional knowledge and practices in cultivation. Ancient tales also speak about the physical, mental and spiritual delights resulting from the consumption of the rice variety.

Only Statement 3 is correct.

• The Square Kilometer Array will not be a single large telescope, but a collection of thousands of dish antennas operating as a single unit. The name, Square Kilometer Array, comes from the original intention to create one square kilometre (one million square metre) of effective area for collecting radio waves. This was meant to be achieved by installing thousands of smaller antennas in a specific array design that would make them function like a single radio telescope.
• The antennas, about 200 of them in South Africa and more than 130,000 in Australia, are being installed in sparsely populated locations, chosen to ensure they are as far away from human activities as possible. This has been done in order to minimise signal interference from undesirable Earth-based sources.
• Though none of the SKA facilities would be located in India, there are immense science and technology gains for the country by participating in the project as a full member.
• The intellectual properties generated by the project, though owned by the SKA Observatory, would be accessible to all the member countries. 

According to the latest report on “The State of the World’s Forests” by the Food and Agricultural Organization of the United Nations (FAO), forests cover 31% of the Earth’s land surface (4.06 billion hectares) out of which approximately one-third (34%) are primary forests.

India has already decided to build a gravitational wave detector to join the international LIGO (Laser Interferometer Gravitational Wave Observatory) network, and is a full member of the ITER project, which is working to harness energy from nuclear fusion reactions. India also has a strong participation in the Large Hadron Collider (LHC), the world’s largest and most powerful particle accelerator that is running some of the most exciting experiments in particle physics.

The Committee on Capital Account Convertibility (CAC) or Tarapore Committee was constituted by the Reserve Bank of India for suggesting a roadmap on full convertibility of Rupee on Capital Account. 

• Bases are a class of chemical substances that exhibit certain characteristic properties.
  • Taste and Feel:
    • Bases often have a bitter taste. Hence statement 1 is correct.
    • Many bases have a slippery or soapy feel when touched.
    • This is especially noticeable with concentrated solutions.
  • pH:
    • Bases have pH values greater than 7 on the pH scale.
    • The pH scale is a measure of the acidity or basicity of a solution, with 7 being neutral, values below 7 indicating acidity, and values above 7 indicating alkalinity (basicity).
  • Turns Litmus Paper Blue:
    • Bases turn red litmus paper blue. Hence statement 2 is correct.
    • Litmus paper is a commonly used indicator that changes color depending on whether a substance is acidic or basic.
  • Electrolyte Properties:
    • Bases typically dissociate or ionize in water to produce hydroxide ions (OH⁻).
    • This makes them electrolytes, as they conduct electricity in solution.
  • Reaction with Acids:
    • Bases react with acids in a chemical reaction known as neutralization.
    • In this reaction, a base and an acid combine to form water and a salt.
  • Feeling of Coolness:
    • Some dilute bases give a cooling sensation when applied to the skin.
    • This property is commonly observed with substances like antacids.
  • Solubility:
    • Many bases are soluble in water, forming aqueous solutions. Hence statement 3 is not correct.
    • However, some bases, especially those containing heavy metal cations, may be less soluble.
  • Corrosive Properties:
    • Concentrated bases can be corrosive and may cause damage to living tissues.
    • Caution is necessary when handling strong bases.

• Electrochemical Machining (ECM) is a non-traditional machining process that involves the controlled removal of metal from a workpiece through the process of electrochemical dissolution. The primary application of ECM in the industry is removing metal from surfaces through controlled dissolution.
• In ECM, a conductive workpiece (anode) and a tool (cathode) are immersed in an electrolyte solution. When a voltage is applied between the workpiece and the tool, metal ions from the workpiece are selectively dissolved into the electrolyte, leading to the removal of material from the workpiece surface.
• ECM is particularly effective for machining complex shapes, intricate patterns, and areas that are difficult to reach with traditional machining methods.
• It is a precise and efficient process that allows for the machining of high-strength and heat-resistant materials.
• ECM is often used in the aerospace, medical, and automotive industries for applications such as turbine blade machining, the production of complex molds, and the creation of intricate components.
• Hence option (c) is the correct answer.

The melting point of a metal is the temperature at which it changes from a solid to a liquid state. Here's a brief overview of the melting points of some common metals.

Hence option (a) is the correct answer.

• A catalyst is a substance that speeds up the rate of a chemical reaction by providing an alternative pathway with a lower activation energy, without itself undergoing any permanent change or being consumed in the reaction. o In other words, a catalyst increases the reaction rate by lowering the energy barrier (activation energy) for the reaction to occur, facilitating the conversion of reactants into products.
• Key points about catalysts:
  • Speeding up Reactions: Catalysts accelerate the rate of chemical reactions by providing an alternative reaction pathway that requires less energy for the formation of products.
  • Remains Unchanged: A catalyst is not consumed in the reaction, and at the end of the reaction, it is regenerated and can be used again in subsequent reactions. Hence statement 1 is not correct.
  • Specific to Reactions: Catalysts are specific to particular reactions or types of reactions. They do not alter the equilibrium position of a reaction but influence the kinetics, making the reaction proceed faster.
  • Not a Reactant or Product: A catalyst is not a reactant, and it does not appear in the stoichiometry of the balanced chemical equation for the reaction. It is not a part of the final products formed.
  • Can be Homogeneous or Heterogeneous: Catalysts can be in the same phase as the reactants (homogeneous catalysis) or in a different phase (heterogeneous catalysis).
• Examples: Common catalysts include transition metals (such as platinum, palladium, and nickel), enzymes in biological systems, acid or base catalysts, and various solid materials with catalytic properties.
• Platinum is indeed a commonly used catalyst in various chemical reactions, particularly in heterogeneous catalysis where the catalyst is in a different phase from the reactants. Platinum's catalytic properties are utilized in reactions such as hydrogenation and dehydrogenation reactions in the chemical industry. Hence statement 2 is correct.

• Gravitational lensing is a phenomenon in which the gravitational field of a massive object, such as a galaxy or a black hole, bends the light coming from a more distant object behind it. This bending of light is a consequence of Einstein's theory of General Relativity.
• When a massive object, like a galaxy or a black hole, is situated between a distant light source (e.g., another galaxy or a quasar) and an observer, its gravitational field acts as a lens.
• The massive object's gravitational field warps the spacetime around it. As light travels through this curved spacetime, it bends, following the curvature caused by the massive object's gravity.
• Depending on the alignment of the observer, the massive object, and the distant light source, gravitational lensing can result in multiple images of the background object. These images may appear as distorted arcs, rings, or even multiple copies of the same object.
• Gravitational lensing has been observed and confirmed through various astronomical observations. One famous example is the gravitational lensing effect around massive galaxy clusters, where the lensing can magnify and distort background galaxies.
• In some cases, individual stars within a galaxy can act as gravitational lenses. This phenomenon, known as microlensing, can be used to detect objects like exoplanets, which might otherwise be challenging to observe directly.
• Gravitational lensing provides a powerful tool for astronomers to study the distribution of mass in the universe, including dark matter, and to investigate distant objects that might otherwise be too faint or distant to observe directly.
• Hence option (b) is the correct answer.

• Viruses are non-living and made up of DNA or RNA surrounded by a protein coat. They can replicate. However, they cannot reproduce on their own. They reproduce when inside a living cell. Therefore viruses pose a special classification problem. Viruses are extremely small and can be seen only under the electron microscope. They are smaller than the smallest bacteria. They can pass through fiters which retain bacteria.
• Virus has a simple structure consisting of a core and a cover. The core particle is the genetic material, either DNA or RNA. The cover is a protein coat called capsid. Hence statement 2 is not correct.
• A virus cannot reproduce by itself. For its reproduction it needs to enter the cell of some organism. From the host cell, it uses the raw material and enzymes and energy generating machinery of the host cell to produce its own DNA. A number of virus particles are thus formed inside the host cell. The host cell bursts to release the new virus particles. Hence statement 1 is correct. 
• Viruses are known to attack bacteria, plants or animals. Viruses which invade bacteria are called bacteriophages. Viruses are highly specific in their relationship with the host and tissue.
  • Viroids are circular RNA molecules, consisting of several hundred nucleotides. They infect plants and even kill them. In plants, they use enzymes of the plant cells to replicate like the viruses do. Hence statement 3 is not correct.
• Viruses are responsible for causing many diseases, including:
  • AIDS, Common cold, Ebola, Herpes, Influenza, Measles, Chickenpox and shingles, Coronavirus disease 2019 (COVID-19), Hepatits, Small Pox, Dengue etc. Antibiotics designed for bacteria have no effect on viruses. Hence statement 4 is correct.

• SDN or sequence specific nuclease (SSN) refers to the practice of cleaving DNA strands to affect the subsequent genome editing. SDN technology takes advantage of targeted DNA break and host’s natural repair mechanisms to introduce specific small changes at the site of the DNA break.
• The basis of current targeted genome editing applications is the capacity to induce a DNA double strand break (DSB) at a selected location in the genome where the modification is intended. Directed repair of the DSB allows for targeted genome editing. Such applications can be applied to generate mutations (targeted mutations or precise native gene editing) as well as precise insertion of genes (cisgenes, intragenes, or transgenes).
• Different approaches can be used to achieve targeted DNA breaks, including Meganucleases (MN), Zinc Finger Nucleases (ZFNs), Transcription Activator-Like Effector Nucleases (TALENs) and the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated proteins (CRISPR/Cas) etc. Collectively, these are often discussed under the acronym site directed nucleases (SDNs), pointing out to the general principle of the technology to use a DNA cutting enzyme (nuclease) for the generation of the targeted (or site directed) DNA break. Hence option (b) is the correct answer.
• Variants of SDN applications are often categorized as SDN-1, SDN-2 and SDN-3 depending on the outcome of the DNA double strand break repair.
  • SDN-1: When the SDN is used in the absence of a DNA repair template (see SDN-2/-3), the outcome is a targeted, non-specific genetic deletion mutation. In this case, the position of the DNA DSB is precisely selected, but the DNA repair by the host cell is random and results in small nucleotide deletions, additions or substitutions. 
  • SDN-2: Is used to generate gene editing mutations. In this case, a SDN is used to generate a targeted DSB and a DNA repair template (a short DNA sequence identical to the targeted DSB DNA sequence except for one or a few nucleotide changes) is used to repair the DSB. The outcome is a targeted and predetermined point mutation in the desired gene of interest.
  • SDN-3: When the SDN is used along with a DNA repair template that contains new DNA sequence (e.g.gene), the outcome of the technology would be the integration of that DNA sequence into the plant genome. The most likely application illustrating the use of SDN-3 would be the insertion of cisgenic, intragenic, or transgenic expression cassettes at a selected genome location.

• An actively photosynthesizing plant has an insatiable need for water. Photosynthesis is limited by available water which can be swiftly depleted by transpiration. The humidity of rainforests is largely due to this vast cycling of water from root to leaf to the atmosphere and back to the soil. The evolution of the C₄ photosynthetic system is probably one of the strategies for maximizing the availability of CO₂ while minimizing water loss. C₄ plants are twice as efficient as C₃ plants in terms of fixing carbon (making sugar). However, a C₄ plant loses only half as much water as a C₃ plant for the same amount of CO₂ fixed. Hence statement 1 is not correct.
• Food, primarily sucrose, is transported by the vascular tissue phloem from a source to a sink. Sugar stored in roots may be mobilized to become a source of food in the early spring when the buds of trees, act as a sink; they need energy for growth and development of the photosynthetic apparatus. Since the source-sink relationship is variable, the direction of movement in the phloem can be upwards or downwards, i.e., bi-directional. This contrasts with that of the xylem where the movement is always unidirectional, i.e., upwards. Hence, unlike the one-way flow of water in transpiration, food in phloem sap can be transported in any required direction so long as there is a source of sugar and a sink able to use, store, or remove the sugar. Hence statement 2 is correct.
• Mycorrhizae are a symbiotic association between plant roots and fungi. The fungal filaments form a network around the young root or they penetrate the root cells. The hyphae have a very large surface area that absorbs mineral ions and water from the soil a much larger volume of soil that perhaps a root cannot do. The fungus provides minerals and water to the roots, in turn, the roots provide sugars and Ncontaining compounds to the mycorrhizae. Some plants have an obligate association with the mycorrhizae. For example, Pinus seeds cannot germinate and establish without the presence of mycorrhizae. Hence statement 3 is not correct.

• Recent Context: A Namibian cheetah gave birth increasing the population amid deaths of Cheetahs at Kuno National Park.
• Project Cheetah, India's ambitious attempt to introduce African cheetahs in the wild in the country was launched in September 2022.
  • The cheetah was declared extinct in India by 1952, the only large carnivore species that went extinct in Independent India. So, its objective was to establish viable cheetah metapopulation in India that allows cheetahs to perform its functional role as top predator.
• Under Project Cheetah, a total of 20 animals were relocated from Namibia and South Africa to Kuno National Park (KNP) in two batches under the government's Project Cheetah. The first batch came in September 2022 and the second in February 2023. As of now, 13 of the original 20 are alive. 20 Cheetah were translocated from Namibia and South Africa. Whereas, Sahel region is defined as the North-Central African semi-arid region between the Sahara Desert and savanna regions. It includes the countries of Burkina Faso, Cameroon, Chad, The Gambia, Guinea Mauritania, Mali, Niger, Nigeria and Senegal. Hence statement 1 is not correct.
• Out of 6 criteria for assessing short-term success, the project has already met four criteria namely:50% survival of introduced cheetahs, Establishment of home ranges, Birth of cubs in Kuno, and Revenue to local communities.
• Implementing Agency of Project Cheetah is National Tiger Conservation Authority (NTCA). Hence statement 2 is correct.
• Funding of project Cheetah is from Project Tiger as well as Compensatory Afforestation Fund Management & Planning Authority (CAMPA).
• Cheetah is protected under Appendix 1 of CITES. The IUCN status of African cheetah is Vulnerable and Asiatic cheetah is Critically endangered. Till now, there were 15 cheetahs at KNP and the tally now stands at 18.

A famous Tamil epic, Silappadikaram, was composed by a poet named Ilango, around 1,800 years ago. It is the story of a merchant named Kovalan, who lived in Puhar and fell in love with a courtesan named Madhavi, neglecting his wife Kannagi. Later, he and Kannagi left Puhar and went to Madurai, where he was wrongly accused of theft by the court jeweller of the Pandya king. The king sentenced Kovalan to death. Kannagi, who still loved him, was full of grief and anger at this injustice, and destroyed the entire city of Madurai.
The Manimekalai was composed by Sattanar around 1,400 years ago. This describes the story of the daughter of Kovalan and Madhavi.
Kalidasa’s best-known poem, the ‘Meghaduta’, in which a monsoon cloud is imagined to be a messenger between the lovers who are separated from one another. Ayurveda is a well-known system of health science that was developed in ancient India. The two famous practitioners of Ayurveda in ancient India were Charak (lst-2nd centuries CE) and Sushruta (c. 4th century CE). Charak Samhita, written by Charak, is a remarkable book on medicine.

Shamans are men and women who claimed magical and healing powers, as well as an ability to communicate with the other world.

The early Buddhist teachings had given great importance to self-effort in achieving Nibbana. Besides, the Buddha was regarded as a human being who attained enlightenment and Nibbana through his own efforts. The concept of the Bodhisatta also developed. The Bodhisattas were perceived as deeply compassionate beings, who accumulated merit through their efforts, but used this not to attain Nibbana and thereby abandon the world, but to help others. The worship of the images of the Buddha and the Bodhisattas became an important part of this tradition. This new way of thinking was called Mahayana -literally, the “great vehicle”. Those who adopted these beliefs described the older tradition as Hinayana or the “lesser vehicle”.

The followers of the older tradition described themselves as the Theravadins, that is, those who followed the path of old, respected teachers, the Theras.

About the Mauryan Period: Gopa and two types of officers, acted as the .intermediaries between the district and the village level administrative units.
The administrative units included a set up at the district level, consisting of a number of villages and, at the same time, each village had its own administrative unit. The officials listed at the level of district during this period were Pradeshta, Rajuka and Yukta, the former being the overall in charge of the district.

The Sudarshan Lake was an artificial reservoir. We know about it from a rock inscription (c. second century CE) in Sanskrit, composed to record the achievements of the Saka ruler Rudradaman. The inscription mentions that the lake, with embankments and water channels, was built by a local Governor during the rule of the Mauryas. However, a terrible storm broke the embankments and water gushed out of the lake. Rudradaman, who was then ruling in the area, claimed to have got the lake repaired using his own resources, without imposing any tax on his subjects. Another inscription on the same rock (c. fifth century) mentions how one of the rulers of the Gupta dynasty got the lake repaired once again.

Except Bagh, all the cities were contemporary to the city of Pataliputra during the period of the Mahajanapadas. Bagh in Madhya Pradesh is known for the Gupta period caves.

Here is an excerpt from Periplus of the Erythraean Sea, composed by an anonymous Greek sailor (c. first century CE): ‘They (i.e., the traders from abroad) send large ships to the Indian markettowns on account of the great quantity and bulk of pepper and Malabathrum (possibly cinnamon, produced in these regions). There are imported here, in the first place, a great quantity of coin; topaz … antimony (a mineral used as a colouring substance), coral, crude glass, copper, tin, lead … There is exported pepper, which is produced in quantity in only one region near these markets … Besides this there are exported great quantities of fine pearls, ivory, silk cloth, … transparent stones of all kinds, diamonds and sapphires, and tortoise shells.’ Archaeological evidence of a bead-making industry, using precious and semi-precious stones, has been found in Kodumanal (Tamil Nadu). It is likely that the local traders brought the stones mentioned in the Periplus from sites, such as these to the coastal ports. Majority of the sea trade share between India and the Roman empire was through the Red Sea or the Erythraean Sea.

• The Pallava kings, who succeeded the Chalukya kings in parts of South India, were also the patrons of art. Mahendravarma I, who ruled in the seventh century, was responsible for building temples at Panamalai, Mandagapattu and Kanchipuram. The inscription at Mandagapattu mentions Mahendravarman I with numerous titles, such as Vichitrachitta (curious-minded), Chitrakarapuli (tiger among artists) and Chaityakari (temple builder), which show his interest in art activities.
• The paintings in these temples too were done at his initiative, though only fragments remain. When the Pandyas came to power, they too patronized art. The Tirumalaipuram caves and the Jaina caves at Sittanvasal are some of the surviving examples.
• A few fragmented layers of paintings can be seen in Tirumalaipuram. In Sittanavasal, the paintings are visible on the ceilings of the shrines, in the verandas, and on the brackets. The tradition of building temples and embellishing them with carvings and paintings continued during the reign of the Chola kings, who ruled over the region from the ninth century to the thirteenth century. But it was in the eleventh century, when the Cholas reached their zenith of power, that masterpieces of the Chola art and architecture began to appear.
• The temples of Brihadeswara at Thanjavur, Gangaikonda Cholapuram and Darasuram in Tamil Nadu were built during the reigns of Rajaraja Chola, his son, Rajendra Chola and Rajaraja Chola II, respectively.

• The Lakshmana temple of Khajuraho, dedicated to Vishnu, was built in 954 by the Chandela king, Dhanga. A Nagara temple, it is placed on a high platform accessed by stairs. There are four smaller temples in the corners, and all the towers or the Shikharas rise high, upward in a curved pyramidal fashion, emphasizing the temple’s vertical thrust ending in a horizontal fluted disc, called an Amalak topped with a Kalash or vase.
• Khajuraho’s temples are also known for their extensive erotic sculptures. The erotic expression is given equal importance in human experience as spiritual pursuit, and it is seen as part of a larger cosmic whole.
• There are many temples at Khajuraho, most of them devoted to the Hindu gods. There are some Jain temples, as well as a Chausanth Yogini temple, which is of interest. Predating the tenth century, this is a temple of small, square shrines of roughly hewn granite blocks, each dedicated to the Devis or the goddesses associated with the rise of the Tantric worship after the seventh century.

• Sheshashayana is a form of Vishnu, where he is shown reclining on the Sheshanaga, called Ananta.
• Nara-Narayan shows the discussion between the human soul and the eternal divine.
• Gajendramoksha is the story of achieving Moksha, symbolically communicated by Vishnu’s suppression of an Asura, who had taken the form of an elephant.

• The Sun temple at dodhera dates back to the ^arly eleventh century and was built by Raja Bhimdev I of the Solanki dynasty.
• There is a massive rectangular stepped tank, called the Surya Kund, in front of it. Proximity of sacred architecture to a water body, such as a tank, a river or a pond, has been noticed right from the earliest times. By the early eleventh century, they had become a part of many temples. This hundred-square-metre rectangular pond is perhaps the grandest temple tank in India.
• The walls of the central small shrine are devoid of carving and are left plain, as the temple faces the east and, every year, at the time of the equinoxes, the Sun shines directly into this central shrine.

• By the; twelfth to the fourteenth centuries, a distinct regional style developed in Assam. The style that came with the migration of the Tais from Upper Burma, mixed with the dominant Pala style of Bengal, and led to the creation of what was later known as the Ahom style in and around Guwahati.
• The Kamakhya temple, a Shakti Peeth, is dedicated to Goddess Kamakhya and was built in the seventeenth century. The Kamakhya temple at the Nilachal hills in Guwahati (Assam) is one of the oldest and the most revered centres of the Tantric practices, dedicated to the Goddess Kamakhya. The temple is the centre of the Kulachara Tantra Marga and the site of the Ambubachi Mela, an annual festival that celebrates the menstruation of the Goddess.

• Ibn Battuta’s description of Daulatabad: In Daulatabad there is a marketplace for male and female singers, which is known as Tarababad. It is one of the greatest and most beautiful bazaars. It has numerous shops and every shop has a door which leads into the house of the owner.
• The shops are decorated with carpets and at the centre of the shop there is a swing on which sits the female singer. She is decked with all kinds of finery and her female attendants swing her. In the middle of the market place, there stands a large cupola, which is carpeted and decorated and in which the chief of the musicians takes his place every Thursday after the dawn prayers, accompanied by his servants and slaves.
• The female singers come in successive crowds, sing before him, and dance until dusk after which he withdraws. In this bazaar, there are mosques for offering prayer. One of the Hindu rulers alighted at the cupola every time he passed by this marketplace, and the female singers would sing before him. Even some Muslim rulers did the same.

Ibn Battuta was amazed by the efficiency of the postal system. He describes the postal system: “In India, the postal system is of two kinds. The horse post, called Uluq, is run by the royal horses stationed at a distance of every four miles. The footpost has three stations per mile. It is called Dawa.”

• According to Francois Bernier (a Frenchman, who was a doctor, political philosopher and historian), one of the fundamental differences between Mughal India and Europe was the lack of private property in land in the former. He was a firm believer in the virtues of private property and saw crown ownership of land as being harmful for both the state and its people. He thought that in the Mughal Empire, the emperor owned all the land and distributed it among his nobles, and that this had disastrous consequences for the economy and the society.
• This perception was not unique to Bernier, but is found in most travellers’ accounts of the sixteenth and the seventeenth centuries. Owing to crown ownership of land, argued Bernier, the landholders could not pass on their land to their children. So, they were averse to any long-term investment in the sustenance and expansion of production. The absence of private property in land had, therefore, prevented the emergence of the class of “improving” landlords (as in the Western Europe) with a concern to maintain or improve the land.