1. Which organelle is known as the powerhouse of the
cell?
2. Name the tissue that store fat in our body.
(a) Connective tissue (b) Adipose tissue
(c) Areolar tissue (d) Skeletal tissue
3. Organelle without a cell membrane is
(a) ribosome (b) nucleus
(c) mitochondria (d) chloroplast
4. Which disease is not transmitted by mosquitoes?
(a) Dengue
(b) Brain fever
(c) Malaria (d) Pneumonia
5. Which division among plants has the simplest
organisms?
6. Name any macronutrients essential for crops.
7. Five kingdom classification has given by
(a) Morgan (b) R. Whittaker
(c) Linnaeus (d) Haeckel
8. What is full form of HIV?
9. Ligament connects a bone with
(a) Skin (b) Muscle
(c) Bone (d) both (b) & (c)
Answers
Answer:
Connective Tissues
Connective tissues are made up of a matrix consisting of living cells and a non-living substance, called the ground substance. The ground substance is made of an organic substance (usually a protein) and an inorganic substance (usually a mineral or water). The principal cell of connective tissues is the fibroblast. This cell makes the fibers found in nearly all of the connective tissues. Fibroblasts are motile, able to carry out mitosis, and can synthesize whichever connective tissue is needed. Macrophages, lymphocytes, and, occasionally, leukocytes can be found in some of the tissues. Some tissues have specialized cells that are not found in the others. The matrix in connective tissues gives the tissue its density. When a connective tissue has a high concentration of cells or fibers, it has proportionally a less dense matrix.
The organic portion or protein fibers found in connective tissues are either collagen, elastic, or reticular fibers. Collagen fibers provide strength to the tissue, preventing it from being torn or separated from the surrounding tissues. Elastic fibers are made of the protein elastin; this fiber can stretch to one and one half of its length and return to its original size and shape. Elastic fibers provide flexibility to the tissues. Reticular fibers are the third type of protein fiber found in connective tissues. This fiber consists of thin strands of collagen that form a network of fibers to support the tissue and other organs to which it is connected. The various types of connective tissues, the types of cells and fibers they are made of, and sample locations of the tissues is summarized in Table 1.
Table 1. Connective Tissues
Tissue Cells Fibers Location
loose/areolar fibroblasts, macrophages, some lymphocytes, some neutrophils few: collagen, elastic, reticular around blood vessels; anchors epithelia
dense, fibrous connective tissue fibroblasts, macrophages, mostly collagen irregular: skin regular: tendons, ligaments
cartilage chondrocytes, chondroblasts hyaline: few collagen fibrocartilage: large amount of collagen shark skeleton, fetal bones, human ears, intervertebral discs
bone osteoblasts, osteocytes, osteoclasts some: collagen, elastic vertebrate skeletons
adipose adipocytes few adipose (fat)
blood red blood cells, white blood cells none blood
Loose/Areolar Connective Tissue
Illustration shows thick collagen fibers and thin elastin fibers loosely woven together in an irregular network. Oval fibroblasts are interspersed among the fibers.
Figure 1. Loose connective tissue is composed of loosely woven collagen and elastic f
ibers. The fibers and other components of the connective tissue matrix are secreted by fibroblasts.
Loose connective tissue, also called areolar connective tissue, has a sampling of all of the components of a connective tissue. As illustrated in Figure 1, loose connective tissue has some fibroblasts; macrophages are present as well. Collagen fibers are relatively wide and stain a light pink, while elastic fibers are thin and stain dark blue to black. The space between the formed elements of the tissue is filled with the matrix. The material in the connective tissue gives it a loose consistency similar to a cotton ball that has been pulled apart. Loose connective tissue is found around every blood vessel and helps to keep the vessel in place. The tissue is also found around and between most body organs. In summary, areolar tissue is tough, yet flexible, and comprises membrane
Explanation: