12-botany- Unit - III & IV Cell Biology And Genetics, Biotechnology

Watson and Crick proposed the double helix DNA model. They are credited with discovering the structure of DNA in 1953. Their model showed that DNA is made up of two strands that are twisted together in a helical shape, resembling a twisted ladder. This discovery was a significant breakthrough in understanding the structure and function of DNA, and it laid the foundation for the field of molecular biology.

Spirulina is a type of blue-green algae that is rich in vitamins and minerals. It is commonly used as a dietary supplement due to its high nutritional content. Spirulina tablets are produced from this organism for human consumption because they provide a convenient and concentrated source of vitamins.

Totipotency refers to the ability of a single plant cell to develop into a complete organism. This means that a single cell has the potential to differentiate and give rise to all the different types of cells and tissues found in an organism. This concept is important in plant tissue culture and cloning techniques, as it allows scientists to regenerate whole plants from a single cell.

Spirulina is the correct answer because it is a type of cyanobacteria that has been classified as a SCP (Super Color Pigment). SCPs are organisms that produce pigments with unique properties, such as intense color and fluorescence. Spirulina is known for its vibrant blue-green color, which is due to the presence of a pigment called phycocyanin. This pigment has various applications, including food coloring and as a natural dye. In addition to its pigment-producing abilities, Spirulina is also rich in nutrients and is often used as a dietary supplement.

Cytokinin is a plant hormone that plays a crucial role in promoting cell division. It stimulates the growth and division of cells, leading to an increase in the number of cells in plant tissues. This hormone is essential for various plant processes such as shoot and root development, leaf expansion, and overall plant growth. Therefore, the function of cytokinin is primarily to enhance cell division in plants.

Hugo de Vries first used the term mutation based on his observation on Oenothera lamarckiana.

Bacillus thuringiensis is the correct answer because it is known to produce a toxic protein called delta endotoxin, which has insecticidal properties. This protein is effective in killing insects and is commonly used in biopesticides for agricultural purposes. Bacillus lactii, Escherichia coli, and Streptomyces griseus do not produce delta endotoxin and are not known for their insecticidal properties.

Nullisomy refers to the loss of both copies of a particular chromosome in a diploid organism. In this case, the correct answer is 2n – 2, which means that in a diploid organism with a total of 2n chromosomes, nullisomy is represented by the absence of two chromosomes. This is because nullisomy results in a loss of both copies of a specific chromosome, leaving only one copy of each of the remaining chromosomes.

Polyethylene glycol (PEG) is a fusogen that is commonly used to fuse two protoplasts together. It is a water-soluble polymer that can form a bridge between the membranes of the protoplasts, allowing them to merge and form a single cell. PEG is often used in cell fusion experiments because it is non-toxic and has a high fusion efficiency. This makes it an ideal choice for fusing protoplasts and studying the effects of cell fusion.

Pseudomonas putida is an engineered bacterium that has the ability to digest crude oil slick. This means that it can break down and metabolize the components of crude oil, which is a valuable trait in cleaning up oil spills and contaminated areas. This bacterium can play a crucial role in environmental remediation efforts by reducing the harmful effects of oil pollution.

Tissue culture is a technique used to grow plants in a controlled environment. It involves taking small pieces of plant tissue and placing them in a nutrient-rich medium to promote growth. One important product that can be formed through tissue culture is artificial synthetic seeds. These seeds are created by encapsulating plant embryos or tissue in a protective coating, allowing them to be stored and transported more easily than traditional seeds. This technology has many applications in agriculture, including the production of disease-free and genetically uniform plants.

During the pachytene stage of prophase I of meiosis, recombination of chromosomes occurs. This is when homologous chromosomes pair up and exchange genetic material through a process called crossing over. This genetic recombination increases genetic diversity and ensures the proper distribution of chromosomes during meiosis.

Neurospora is a genus of filamentous fungi that has been extensively studied in genetics and biochemistry. It is known for its ability to grow on minimal media, which is a medium that lacks certain essential nutrients such as amino acids. Biochemical mutants of Neurospora fail to synthesize certain amino acids, indicating that they have mutations in the genes responsible for amino acid synthesis. This makes Neurospora a valuable model organism for studying amino acid metabolism and biosynthesis.

RNA is universally present in all organisms except in DNA viruses. DNA viruses do not have RNA as their genetic material. Instead, their genetic material is made up of DNA. This is in contrast to other organisms, such as bacteria, algae, and TMV (Tobacco Mosaic Virus), which have RNA as a fundamental component of their genetic material.

Restriction enzymes are proteins that can recognize and bind to specific nucleotide sequences in DNA. Once bound, they cleave the DNA at or near the recognition sequence, resulting in the formation of smaller DNA fragments. Therefore, the correct answer is "nucleotide sequence" as restriction enzymes cleave DNA molecules only at specific nucleotide sequences.

Electroporation is a process used to introduce a foreign gene into a cell. It involves the application of an electric field to create temporary pores in the cell membrane, allowing the foreign gene to enter the cell. This method is commonly used in molecular biology and genetic engineering to transform cells and introduce new genetic material. It is a quick and efficient way to deliver genes into cells and has been widely used in research and biotechnology applications.

Somatic hybrids are produced through protoplasmic fusion, which involves the fusion of protoplasts from different plant species or varieties. Protoplasts are plant cells with their cell walls removed, allowing them to fuse together and form a hybrid cell. This fusion can result in the combination of desirable traits from both parent plants, leading to the production of somatic hybrids with improved characteristics. This technique is commonly used in plant breeding to create new varieties with desired traits, such as disease resistance or increased yield.

The term "chromosome" was introduced by Waldeyer.

The correct answer is "fifty". This means that there are approximately fifty transgenic plants available today.

The width of a DNA molecule is 20 Å.

Bacterial cells have more than 70 tRNAs. tRNA, or transfer RNA, is responsible for carrying amino acids to the ribosome during protein synthesis. Each tRNA molecule is specific to a particular amino acid, and there are more than 70 different types of amino acids found in bacteria. Therefore, there must be more than 70 tRNAs in bacterial cells to ensure that each amino acid is properly transported and incorporated into proteins.

Restriction enzymes are proteins that are produced by bacteria. These enzymes are used by bacteria as a defense mechanism against foreign DNA, such as that from viruses. They recognize specific DNA sequences and cut the DNA at those sites. This ability to cut DNA at specific sequences is used in molecular biology techniques such as DNA cloning and genetic engineering. While other organisms, such as yeast, may have similar enzymes, restriction enzymes are primarily synthesized by bacteria.

Bridges is the correct answer because he was the first to provide experimental evidence that genes are carried by the chromosomes. He conducted experiments on fruit flies, specifically studying the inheritance of sex-linked genes. Through his research, Bridges demonstrated that specific genes were located on specific chromosomes, providing crucial evidence for the chromosome theory of inheritance.

The given answer, 7:1:1:7, represents the coupling test cross ratio. This ratio indicates the likelihood of certain traits being inherited together. In this case, it suggests that two traits are tightly linked and are likely to be inherited together, while the other two traits are also linked but to a lesser extent. This ratio can be used to understand the genetic linkage between different traits and can be helpful in genetic research and breeding programs.

mRNA, or messenger RNA, is a type of RNA molecule that carries genetic information from the DNA to the ribosomes, where it is used as a template for protein synthesis. It makes up only a small percentage of the total RNA content in a cell, typically ranging from 3% to 5%. The majority of RNA in a cell is composed of ribosomal RNA (rRNA) and transfer RNA (tRNA), which have different roles in protein synthesis. Therefore, mRNA represents a relatively small fraction of the RNA content in a cell.

Drosophila melanogaster, also known as fruit flies, have four chromosomes in their gametes. Chromosomes are structures that contain genetic information in the form of DNA. Gametes are reproductive cells, such as sperm and eggs, that carry half the number of chromosomes as compared to the body cells. In fruit flies, the gametes have four chromosomes, which means that when a sperm fertilizes an egg, the resulting offspring will have a total of eight chromosomes.