8TH SECTION - B
Note: Answer the following questions:
21. State the types of tissues.
22. Mention the function of alveoli.
23. Seeds of gymnosperm plants are naked. Why?
24. How many classes are there in bryophytes? What are they?
25. Write the types of bacteria based on their shape.
26. What are pathogens?
27. What is global warming?
28. Why oxygen is called as “acid producer"?
29. What is pollution?
30. What is tarnishing? Give an example.
31. What is ductility?
32. Write the symbols for the following elements:
a) Cadmium
b)Calcium
c)Magnesium
d) Gold
pls tell quickly
Answers
Answer:
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Explanation:
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Answer:
21. There are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue.
22.The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. ... Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset).
23.Gymnosperms are those seed plants in which the seeds remain exposed over the surface of the megasporophylls because the latter are not folded to form pistils and thus lack ovary. Flowers are absent and thus fruits are not formed.
24.In the 2000 classification scheme the phylum Bryophyta is divided into six classes: Takakiopsida, Sphagnopsida, Andreaeopsida, Andreaeobryopsida, Polytrichopsida and Bryopsida.
25.Bacteria are classified into five groups according to their basic shapes: spherical (cocci), rod (bacilli), spiral (spirilla), comma (vibrios) or corkscrew (spirochaetes). They can exist as single cells, in pairs, chains or clusters. Bacteria are found in every habitat on Earth: soil, rock, oceans and even arctic snow.
26.A pathogen is defined as an organism causing disease to its host, with the severity of the disease symptoms referred to as virulence. Pathogens are taxonomically widely diverse and comprise viruses and bacteria as well as unicellular and multicellular eukaryotes.
27.Global warming is the long-term heating of Earth's climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere.
28.Where did oxygen get its name? The name oxygen comes from the Greek word "oxygenes" meaning "acid producer". It was called this because early chemists thought that oxygen was necessary for all acids. There are three stable isotopes of oxygen.
29.Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat, or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.
30.Tarnish is defined as to spoil or to discolor the surface of a piece of metal. An example of to tarnish is to expose silver to sulfur and air. ... Being in the ground for so long tarnished the old coins.
31.Ductility is a mechanical property commonly described as a material's amenability to drawing. In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stress before failure.
32.
a)Cd
b)Ca
c)Mg
d)Au