Why is yeast placed in multicellular organisms

PMC

Multiple choice questions

Tick ​​the correct answer (s). The solutions can be found on the back.

  1. cannot survive without other cells.

  2. are eukaryotic organisms.

  3. are surrounded by a lipid membrane.

  • Hydrophilic molecules

  1. accumulate in an aqueous solution.

  2. it is difficult for biological membranes to pass through.

  3. are small.

  1. is the basic building block of organic molecules.

  2. hardly occurs in living things.

  3. is preferred by living things as 12C isotope incorporated.

  1. was the first cell on earth.

  2. is a bacterium.

  3. is the common ancestor of all living things currently in existence.

  • A differentiated cell

  1. is specialized in a certain task in the case of multicellular people.

  2. is totipotent.

  3. has no nucleus.

  1. are real cells.

  2. ferment instead of breathing because they live without oxygen.

  3. are all capable of photosynthesis.

  1. are bacteria.

  2. correspond roughly to the size of the cell nucleus.

  3. are mitochondria that have evolved over the course of evolution.

  • With the transmission electron microscope

  1. no living tissue can be examined.

  2. only black and white images can be generated.

  3. In contrast to the scanning electron microscope, only a low resolution can be achieved.

  1. gains energy through fermentation.

  2. is an intracellular parasite.

  3. consists of bacterial DNA.

  • A eukaryotic cell

  1. has a nucleus with a nuclear envelope.

  2. has no compartments.

  3. cannot be seen under the optical microscope.

reply

  • c) All cells are separated from the environment by a membrane, which for the most part consists of lipids. Organic hydrophilic molecules are separated out in this way. The term cell doesn't just refer to eukaryotes. Many organisms only consist of a single cell.

  • b) The hydrophobic or hydrophilic properties of a molecule are not determined by its size, but rather by its chemical groups. Hydrophobic molecules accumulate in aqueous solutions. Membranes are effective barriers to hydrophilic molecules.

  • a) and c) Organic molecules largely consist of carbon or a carbon skeleton. During photosynthesis, carbon is fixed from the atmosphere, and this becomes 12C isotope preferred.

  • c) LUCA is an acronym and denotes the last common ancestor of all current living beings on earth. It is not clear whether LUCA was a eukaryote, a bacterium, or an archaea. LUCA was certainly a cell, but not the first. There were certainly other organisms before LUCA.

  • a) The division of labor among the multicellular cells made it necessary to differentiate between the cells. These cells are very different and take on specific tasks within the organism. In contrast to the unicellular cells, the differentiated cells have lost their totipotent properties. With the exception of erythrocytes, most differentiated and undifferentiated cells have a nucleus.

  • a) Bacteria are mainly single cells. They have a simple structure, without a nucleus and without compartments. They are still cells. Your metabolism is very variable. Some bacteria breath, with or without oxygen, and some do fermentation, etc. Only some of them do photosynthesis.

  • b) Chloroplasts are large cell organelles about 10 µm in length. Like mitochondria, they emerged from the symbiosis of a bacterium with an ancestor of the eukaryotes and did not evolve from mitochondria. Chloroplasts are derived from bacteria, but they are not bacteria themselves.

  • a and b) Electron microscopes have a high vacuum inside, which prevents the examination of fresh specimens containing water. The resulting image in the microscope is binary (an electron is detected or not detected), so it is basically black and white. In addition, the transmission electron microscope has a higher resolution than the scanning electron microscope.

  • b) Viruses are organisms on the verge of life. They have no metabolism of their own, they do not gain energy, and they neither breathe nor ferment. Bacteriophages are intracellular parasites that inject their genetic material, DNA or RNA, into bacteria. However, the genome is not bacterial. In addition, bacteriophages have capsid proteins and therefore do not consist only of nucleic acids.

  • a) The presence of a membrane-covered nucleus is a hallmark of eukaryotes. They also have extensive cell compartments. Eukaryotes are a few micrometers in size and can be clearly seen under an optical microscope.