- Which of the numbered structures shown in B are absent in A?
- The image given in Figure A is of a Spiderworts leaf. they grow in a part of Canada
where the sun shines in the morning and it is cloudy in the afternoon. Describe what
changes you would expect to see to the structures in the plant leaf during the day. How
would these changes compare to a plant that grows in a hot, sunny days and cold, dry
nights?
5.7 Summary DUMMY
- Cells which are similar in structure group together to form tissues performing a partic-
ular function. Tissues form organs which combine to allow organisms to exist. - Plant and animal cells have structures related to their functions.
- Plant tissues are broadly divided into Dividing or Meristematic and Permanent tissues.
- Meristematic cells are small, have high amounts of cytoplasm and a large nucleus to
assist in their role in cell division. - Permanent tissues are further divided into simple permanent (which have only one
type of cell) and complex permanent (which have different types of cell coming to-
gether to perform a particular function). The simple permanent tissues include (with
their function in brackets): Epidermis (protection), Parenchyma (storage), Collenchyma
(support) and Sclerenchyma tissues (strength and structural support). Complex tissues
are made up of the xylem and phloem. - Xylem tissue is important in the transport of water and mineral salts. Phloem tissue is
structured to allow the transport of organic compounds required for the plant (typically
in the form of sucrose). Together the parenchyma, collenchyma and sclerenchyma are
referred to as ground tissue. The xylem and phloem make up the vascular tissue. - Animal tissues are made up of epithelial, connective, muscle and nerve tissue. Ep-
ithelium is made up of flat squamous cells, cuboidal cells or columnar cells in single
or multiple layers. Epithelial cells are involves in secretion of enzymes, protective
substances such as mucus and they provide a supportive function - Muscle tissue is made up of cardiac muscle, skeletal muscle and smooth muscle. Car-
diac and skeletal muscle are striated. Smooth muscle and cardiac muscle are involun-
tary muscles whereas skeletal muscle is under voluntary control. - Connective tissues are composed of areolar, fibrous, cartilage, bone tissue and blood.
They provide strength and support, reduce friction and act as shock absorbers. - Blood is made up of red blood cells (transport oxygen), white blood cells (responsible
for immune response) and platelets (important in blood clotting). - Nerve tissue is responsible for receiving stimuli from the environment (sensory neu-
rons), processing it (interneurons) and sending impulses to muscles or glands (motor
neurons) so that we can respond to the stimuli. - Traditional healers and traditional medicine is an application of indigenous knowledge
of plant and animal tissues. - Modern Biotechnology is focused on a variety of applications of technology. Vaccines
and antibiotics enhance the body’s immunity. - Immunity relies on the natural mechanisms (skin, mucus etc) as well as cellular mech-
anisms (T-cells and B-cells) fighting viral and bacterial infections. Vaccines rely on
T-memory-cell derived immunity to fight subsequent infections. - Blood transfusion is a way of replacing lost blood. It requires accurate blood type
matching.
154 5.7. Summary