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Sindh Botany 2021 — Solved Past Paper with Answers

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Q1. The solution having low concentration as compared to the cell sap

  • A. Hypertonic
  • B. Hypotonic✓
  • C. Isotonic
  • D. Solute potential

Explanation: Hypotonic. A hypotonic solution has a lower solute concentration compared to the intracellular solute concentration. When a red blood cell is placed in a hypotonic solution, there will be a net movement of free water into the cell.

Why the other options are wrong
  • A. A hypertonic solution is any external solution that has a high solute concentration and low water concentration compared to body fluids. In a hypertonic solution, the net movement of water will be out of the body and into the solution.
  • C. An isotonic solution has the same or very similar concentration of solute as another solution, meaning the water flow will reach equilibrium.
  • D. Solute potential (Ψs), also called osmotic potential, is negative in a plant cell and zero in distilled water. Typical values for cell cytoplasm are –0.5 to –1.0 MPa. Solutes reduce water potential (resulting in a negative Ψw) by consuming some of the potential energy available in the water.

Q2. In terms of number of chromosomes, the endosperm of seed is:

  • A. Haploid
  • B. Quadreploid
  • C. Tripoid✓
  • D. Diploid

Explanation: Endosperm is formed during the double fertilization. It is triploid because it is formed when one of the two sperm that is haploid enters inside the embryo sac & fuses with two polar nuclei (each polar nuclei is haploid). So the endosperm formed is triploid.

Why the other options are wrong
  • A. Endosperm is formed during the double fertilization. It is triploid because it is formed when one of the two sperm that is haploid enters inside the embryo sac & fuses with two polar nuclei (each polar nuclei is haploid). So the endosperm formed is triploid.
  • B. Endosperm is formed during the double fertilization. It is triploid because it is formed when one of the two sperm that is haploid enters inside the embryo sac & fuses with two polar nuclei (each polar nuclei is haploid). So the endosperm formed is triploid.
  • D. Endosperm is formed during the double fertilization. It is triploid because it is formed when one of the two sperm that is haploid enters inside the embryo sac & fuses with two polar nuclei (each polar nuclei is haploid). So the endosperm formed is triploid.

Q3. Two polynucleotide chains of DNA are apart from each other by:

  • A. 3 A
  • B. 34 A
  • C. 20 A✓
  • D. 4 A

Explanation: DNA is a double helical structure which is made up of two polynucleotide chains and these chains are connected with each other via hydrogen bonds formed between two nitrogenous base know as base pair, the distance between two base pairs is 0.34 nm (nano meter).

Why the other options are wrong
  • A. DNA is a double helical structure which is made up of two polynucleotide chains and these chains are connected with each other via hydrogen bonds formed between two nitrogenous base know as base pair, the distance between two base pairs is 0.34 nm (nano meter).
  • B. DNA is a double helical structure which is made up of two polynucleotide chains and these chains are connected with each other via hydrogen bonds formed between two nitrogenous base know as base pair, the distance between two base pairs is 0.34 nm (nano meter).
  • D. DNA is a double helical structure which is made up of two polynucleotide chains and these chains are connected with each other via hydrogen bonds formed between two nitrogenous base know as base pair, the distance between two base pairs is 0.34 nm (nano meter).

Q4. A cell division without spindle is:

  • A. Amitosis✓
  • B. Apomixis
  • C. Meiosis
  • D. Mitosis

Explanation: Amitosis is direct cell division by simple cleavage of the nucleus, without spindle formation or the appearance of chromosomes.

Why the other options are wrong
  • B. Apomixis is the process of asexual reproduction through seeds that is increasingly being viewed as a deregulation of sexual reproduction rather than an independent pathway.
  • C. Meiosis is a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes (the sex cells, or egg and sperm).
  • D. Mitosis is the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division. Mitosis is generally followed by equal division of the cell's content into two daughter cells that have identical genomes.

Q5. This biome is called the "bread basket" of the world:

  • A. Savanna
  • B. Tundra
  • C. Grass land✓
  • D. Tropical Rain forest

Explanation: Mid-latitude grasslands are known as the “Bread Basket” of the world.

Why the other options are wrong
  • A. The savanna biome, which is a type of grassland biome, consists of areas of open grassland with very few trees. There are two kinds of savannas: tropical and semi-tropical savannas.
  • B. The tundra is the coldest of the biomes. It also receives low amounts of precipitation, making the tundra similar to a desert. Tundra is found in the regions just below the ice caps of the Arctic, extending across North America, to Europe, and Siberia in Asia.
  • D. Tropical rainforests are the most biologically diverse terrestrial ecosystems in the world. The Amazon rainforest is the world's largest tropical rainforest. It is home to around 40,000 plant species, nearly 1,300 bird species, 3,000 types of fish, 427 species of mammals, and 2.5 million different insects.

Q6. This group of plants is found in soil of high salt concentration:

  • A. Hydrophytes
  • B. Halophytes✓
  • C. Mesophytes
  • D. Xerophytes

Explanation: Mesophytes (hygrophytes) are ordinary plants that mostly survive and dominate a well-watered habitat. Mesophytes possess hydathodes or glandular hairs. Xerophytes are plants that survive and dominate in water-scarce habitats, such as deserts or windy areas.

Why the other options are wrong
  • A. Hydrophytes are plants that are especially suited for and have adapted to living in aquatic environments. i They are also referred to as macrophytes to differentiate them from algae and other microscopic plants. Hydrophytes are found in one of three ways: emergent, submerged or floating.
  • C. Mesophytes (hygrophytes) are ordinary plants that mostly survive and dominate a well-watered habitat. Mesophytes possess hydathodes or glandular hairs. Xerophytes are plants that survive and dominate in water-scarce habitats, such as deserts or windy areas.
  • D. Mesophytes (hygrophytes) are ordinary plants that mostly survive and dominate a well-watered habitat. Mesophytes possess hydathodes or glandular hairs. Xerophytes are plants that survive and dominate in water-scarce habitats, such as deserts or windy areas.

Q7. The breakdown of rocks due to environmental action is called:

  • A. Topography
  • B. Weathering✓
  • C. Pedology
  • D. Edaphic

Explanation: Weathering is a term which describes the general process by which rocks are broken down at the Earth's surface into such things as sediments, clays, soils and substances that are dissolved in water.

Why the other options are wrong
  • A. The study of the shape of the surface of the land, with all its ups and downs, is known as topography. The word topography derives from the greek “topo,” meaning place, and “graphia,” meaning to write or to record. Maps that represent topography are known as topographic maps.
  • C. Pedology is a branch of soil science focusing on the formation, morphology, and classification of soils as bodies within the natural landscape.
  • D. Edaphology is concerned with the influence of soils on living beings, particularly plants. It is one of two main divisions of soil science, the other being pedology. Edaphology includes the study of how soil influences humankind's use of land for plant growth as well as people's overall use of the land.

Q8. The producer of a pond ecosystem is:

  • A. Bacteria
  • B. Zooplankton
  • C. Phytoplankton✓
  • D. Fungi

Explanation: Producers in a pond ecosystem are phytoplanktons and aquatic plants, and the primary consumers are zooplanktons that feed on the producers. The secondary consumers are small aquatic animals that depend on primary consumers for their food. Tertiary consumers are insects, larvae, fish, bird, etc.

Why the other options are wrong
  • A. Producers in a pond ecosystem are phytoplanktons and aquatic plants, and the primary consumers are zooplanktons that feed on the producers. The secondary consumers are small aquatic animals that depend on primary consumers for their food. Tertiary consumers are insects, larvae, fish, bird, etc.
  • B. Producers in a pond ecosystem are phytoplanktons and aquatic plants, and the primary consumers are zooplanktons that feed on the producers. The secondary consumers are small aquatic animals that depend on primary consumers for their food. Tertiary consumers are insects, larvae, fish, bird, etc.
  • D. Producers in a pond ecosystem are phytoplanktons and aquatic plants, and the primary consumers are zooplanktons that feed on the producers. The secondary consumers are small aquatic animals that depend on primary consumers for their food. Tertiary consumers are insects, larvae, fish, bird, etc.

Q9. This condon is start condon:

  • A. AUG✓
  • B. UGA
  • C. UAA
  • D. UAG

Explanation: The codon AUG is called the START codon as it the first codon in the transcribed mRNA that undergoes translation. AUG is the most common START codon and it codes for the amino acid methionine (Met) in eukaryotes and formyl methionine (fMet) in prokaryotes.

Why the other options are wrong
  • B. The codon AUG is called the START codon as it the first codon in the transcribed mRNA that undergoes translation. AUG is the most common START codon and it codes for the amino acid methionine (Met) in eukaryotes and formyl methionine (fMet) in prokaryotes.
  • C. The codon AUG is called the START codon as it the first codon in the transcribed mRNA that undergoes translation. AUG is the most common START codon and it codes for the amino acid methionine (Met) in eukaryotes and formyl methionine (fMet) in prokaryotes.
  • D. The codon AUG is called the START codon as it the first codon in the transcribed mRNA that undergoes translation. AUG is the most common START codon and it codes for the amino acid methionine (Met) in eukaryotes and formyl methionine (fMet) in prokaryotes.

Q10. Meristem responsible for secondary growth:

  • A. Apical
  • B. Lateral✓
  • C. Intercalary
  • D. Cork

Explanation: The process of secondary growth is controlled by the lateral meristems in both stems and roots. Lateral meristems include the vascular cambium and, in woody plants, the cork cambium (cambium is another term for meristem).

Why the other options are wrong
  • A. Apical meristem, region of cells capable of division and growth in the root and shoot tips in plants. Apical meristems give rise to the primary plant body and are responsible for the extension of the roots and shoots.
  • C. Intercalary meristem is a type of primary meristematic tissue containing cells that can divide and promote the growth of the plant. They are located at the base of internodes. The function of the intercalary meristem is to promote the lengthening of the stem and increase the height of the plant.
  • D. Phellogen layer or cork cambium is a dividing zone of cells that forms phellem to the outside and phelloderm to the inside. In other words, it forms the outer bark. This cambial zone is constantly on the move outward as the tree grows.

Q11. During the process the translation, cells use this to make protein:

  • A. RNA✓
  • B. Nucleus
  • C. Chromosomes
  • D. DNA

Explanation: During translation, ribosomal subunits assemble together like a sandwich on the strand of mRNA, where they proceed to attract tRNA molecules tethered to amino acids (circles). A long chain of amino acids emerges as the ribosome decodes the mRNA sequence into a polypeptide, or a new protein.

Why the other options are wrong
  • B. During translation, ribosomal subunits assemble together like a sandwich on the strand of mRNA, where they proceed to attract tRNA molecules tethered to amino acids (circles). A long chain of amino acids emerges as the ribosome decodes the mRNA sequence into a polypeptide, or a new protein.
  • C. During translation, ribosomal subunits assemble together like a sandwich on the strand of mRNA, where they proceed to attract tRNA molecules tethered to amino acids (circles). A long chain of amino acids emerges as the ribosome decodes the mRNA sequence into a polypeptide, or a new protein.
  • D. During translation, ribosomal subunits assemble together like a sandwich on the strand of mRNA, where they proceed to attract tRNA molecules tethered to amino acids (circles). A long chain of amino acids emerges as the ribosome decodes the mRNA sequence into a polypeptide, or a new protein.

Q12. The best soil for plant growth is:

  • A. Sand
  • B. Clay
  • C. Loam✓
  • D. Silt

Explanation: Loamy soil is best for plant growth as it has high water retention capacity thus it retains water for long and also retains the nutrients which is required for plant growth.

Why the other options are wrong
  • A. Loamy soil is best for plant growth as it has high water retention capacity thus it retains water for long and also retains the nutrients which is required for plant growth.
  • B. Loamy soil is best for plant growth as it has high water retention capacity thus it retains water for long and also retains the nutrients which is required for plant growth.
  • D. Loamy soil is best for plant growth as it has high water retention capacity thus it retains water for long and also retains the nutrients which is required for plant growth.

Q13. Total aggregation of gene in a population is called:

  • A. Chromosomes
  • B. Gene pool✓
  • C. Population
  • D. Multiple gene

Explanation: The sum total of all the versions of all of the genes in a species is called the gene pool of the species. Genotype is an individual's collection of genes. A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell.

Why the other options are wrong
  • A. The sum total of all the versions of all of the genes in a species is called the gene pool of the species. Genotype is an individual's collection of genes. A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell.
  • C. The sum total of all the versions of all of the genes in a species is called the gene pool of the species. Genotype is an individual's collection of genes. A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell.
  • D. The sum total of all the versions of all of the genes in a species is called the gene pool of the species. Genotype is an individual's collection of genes. A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell.

Q14. At High temperature plants produce these to preserve enzymes

  • A. Fructans
  • B. Unsaturated fatty acids
  • C. Heat shock proteins✓
  • D. Phytoalexin

Explanation: Plants respond to heat stress by activating heat shock factors and also other molecular players. In particular, hormones as chemical messengers are involved. Among the hormones that plants produce are the brassinosteroids, which primarily regulate their growth and developments.

Why the other options are wrong
  • A. Plants respond to heat stress by activating heat shock factors and also other molecular players. In particular, hormones as chemical messengers are involved. Among the hormones that plants produce are the brassinosteroids, which primarily regulate their growth and developments.
  • B. Plants respond to heat stress by activating heat shock factors and also other molecular players. In particular, hormones as chemical messengers are involved. Among the hormones that plants produce are the brassinosteroids, which primarily regulate their growth and developments.
  • D. Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms.

Q15. The genetic makeup of any individual is called:

  • A. Allelomorph
  • B. Phenotype
  • C. Synapsis
  • D. Genotype✓

Explanation: Genotype' is the genetic makeup of an individual or a variety. It is the alleles of the genes that determine the phenotype of an individual.

Why the other options are wrong
  • A. Definitions of allelomorph. (genetics) either of a pair (or series) of alternative forms of a gene that can occupy the same locus on a particular chromosome and that control the same character. synonyms: allele. types: dominant, dominant allele.
  • B. Phenotype refers to an individual's observable traits, such as height, eye color and blood type. A person's phenotype is determined by both their genomic makeup (genotype) and environmental factors.
  • C. Synapsis and crossing-over mechanisms increase genetic diversity by recombining combinations of gene alleles on a single chromosome which always segregate together.

Q16. During this stage of mitosis chromosomes arrange on equatorial plate:

  • A. Prophase
  • B. Anaphase
  • C. Metaphase✓
  • D. Telophase

Explanation: Metaphase. Next, chromosomes assume their most compacted state during metaphase, when the centromeres of all the cell's chromosomes line up at the equator of the spindle.

Why the other options are wrong
  • A. Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses.
  • B. In anaphase, the sister chromatids separate from each other and are pulled towards opposite ends of the cell. The protein “glue” that holds the sister chromatids together is broken down, allowing them to separate. Each is now its own chromosome. The chromosomes of each pair are pulled towards opposite ends of the cell.
  • D. Telophase is the fifth and final phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. Telophase begins once the replicated, paired chromosomes have been separated and pulled to opposite sides, or poles, of the cell.

Q17. The two chromatids of the same chromosome are called:

  • A. Chromonema
  • B. Kinetochore
  • C. Sister chromatids✓
  • D. Centromere

Explanation: As a cell prepares to divide, it must make a copy of each of its chromosomes. The two copies of a chromosome are called sister chromatids. The sister chromatids are identical to one another and are attached to each other by proteins called cohesins.

Why the other options are wrong
  • A. 1. the coiled mass of threads visible within a nucleus at the start of cell division. 2. a coiled chromatin thread within a single chromosome.
  • B. A kinetochore (/kɪˈnɛtəkɔːr/, /-ˈniːtəkɔːr/) is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart.
  • D. The centromere appears as a constricted region of a chromosome and plays a key role in helping the cell divide up its DNA during division (mitosis and meiosis). Specifically, it is the region where the cell's spindle fibers attach.

Q18. Germination of seed inside the fruit is called:

  • A. Epigeal
  • B. Viviparous✓
  • C. Hypogeal
  • D. Hypocotyl

Explanation: Vivipary is the germination of seed within the fruit.

Why the other options are wrong
  • A. Epigeal germination: In this, the cotyledons of the seeds are pushed above the soil due to elongation of the hypocotyl. Example: Bean, Tomato, Pumpkin. Hypogeal germination: In this, the cotyledons of the seeds remain below the soil as the epicotyl elongates pushing the plumule out of the soil.
  • C. Hypogeal germination refers to the type of germination process that happens below the ground. In this form of germination the cotyledons remain below the soil. The plumule, or primitive shoot tip, that arises from the seed embryo is visible above ground. The plumule pushes its way to the surface by pressing upward.
  • D. A hypocotyl is a germinating seedling's stem, normally found underneath the seed leaves but above the root. This leaf-like structure tends to grow in response to light stimulation. Because the hypocotyl is the main extension organ, it gradually develops into the stem as the plant continues to grow.

Q19. Movement of plant, unrelated to the direction of stimuli is known as:

  • A. Nutation
  • B. Turgor
  • C. Tropic
  • D. Nastic✓

Explanation: Nastic movements are movements that are not specifically directed towrds or away from the stimuli. For example, some flowers bloom in the morning, close during the night. The movement of opening and closing of flowers is not directed towards the stimuli (the sun).

Why the other options are wrong
  • A. Nutation, often called circumnutation, is a particular class of nastic movements, in which the plant organ successively bends in different directions, resulting in an apparent oscillatory swinging motion.
  • B. Turgor movements in plants are often reversible and are caused by changes in the “turgor pressure” in specific cells. For example, some plants exhibit different flower positions during the day than at night, some beans, often display different leaf positions from day to night.
  • C. Tropic movement is the movement of the plant in response to the stimulus present in the environment, this movement is in response to root and shoot growth. They are mainly of five types: Phototropism - It is the movement of a plant in response to light, they will grow towards the direction of the light.

Q20. These tissues are commonly known as conducting tissue:

  • A. Vascular tissues✓
  • B. Meristem
  • C. Cork Cambium
  • D. Ground tissues

Explanation: A conducting tissue is also called the vascular tissue. It provides passage for water and minerals to move up and down in the plant. Xylem and phloem are the two types of the conducting tissues.

Why the other options are wrong
  • B. The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants.
  • C. The vascular cambium and cork cambium are secondary meristems that are formed in stems and roots after the tissues of the primary plant body have differentiated. The vascular cambium is responsible for increasing the diameter of stems and roots and for forming woody tissue. The cork cambium produces some of the bark.
  • D. Ground tissue is every one of the tissues aside from the vascular packs and the epidermis. They structure the inside of organs, with the exemption being the vascular framework. They include basic tissues, for example, sclerenchyma, collenchyma and parenchyma.

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