CH5 Biological systems

Question 1

xylem

Answer 1

tubes that transports water and minerals in one direction, from the roots to the leaves
- made from dead cells where the nucleus and cytoplasm disintegrate
- strengthened on the outside by lignin
- perforations in the sides to allow transport in and out
- non living when at maturity

Question 2

plant tissues

phloem

Answer 2

tubes that transports sugars and other nutrients in two directions, to all the cells of the plant
- composed of a sieve tube ( no nucleus. long connected structures) and a companion cell (nucleus. connected to sieve tube plasmodesmata.)
- living tissue which contains nucleus, cytoplasm and mitochondria.

Question 3

plant tissues

guard cell

Answer 3

a pair of curved cells that surround a stoma. when hot they lose turgor pressure and become flaccid, closing the stomata to limit water loss.

Question 4

what is lignin

Answer 4

enhances cell wall rigidity, hydrophobic properties and promotes minerals transport through the vascular bundles in plant.

Question 5

plant tissues

what are vascular plants?

Answer 5

flowering plants, shrubs and trees, conifers or pines, and ferns are all vascular plants.
- examples of non vascular plants are liverwort and mosses.
- Plants that have vascular tubes to transport water and food around the plant

Question 6

what are the three primary organs present in vascular plants?

Answer 6

• leaves
• stems
• roots

Question 7

what is a vascular bundle?

Answer 7

a vascular bundle is made of xylems( woody tissue for the transport of water) and phloems( a living tissue for the transport of sugars produced by photosynthesis)

Question 8

what are the three layers in leaves?

Answer 8

• upper epidermis
• mesophyll
• lower epidermis

Question 9

what is the epidermis?

Answer 9

• outer layer of leaf
• transparent
• excretes a protective cuticle to prevent evaporation and protect the leaf
• ## contains stomata (singular = stoma) for gas exchange.

Question 10

what is mesophyll?

Answer 10

there is palisade mesophyll near the top with lots of chloroplasts for photosynthesis.

and spongy mesophyll near the bottom with lots of gaps to allow gas exchange

Question 11

what are stomata?

Answer 11

• tiny pores in the epidermis (outer layer of leaves) that let gases ( and water) in and out of the leaf
• pore is called a stoma. the cells on either side are called guard cells
• they can close with the help of guard cells to prevent loss of water.
• typically closed at night

Question 12

what happens in the roots?

Answer 12

• water and nutrient uptake from the soil
• roots hairs are long and thin for a high SA:V
• oxygen- found in air in the soil, diffuses into the roots
• other functions include, they anchor the plant and they store energy

Question 13

what is the transpiration stream?

Answer 13

• it is the continuous flow of water through the plant.
• it is driven by the evaporation of water from leaves.
• as water evaporates out of the leaves through the stomata, the liquid inside becomes more concentrated. this draws more water in via ozmosis.

Question 14

factors that affect transpiration

Answer 14

• the number and degree of open stomata
• Humidity- the more humidoty the less transpiration as there is more water in the air
  - temperature - the wamer it is the more transpiration occurs as water is evaporated
• wind- the more wind the greater transpiration as the air keeps moving and taking water vapor with it.

Question 15

what is adhesion?

Answer 15

the attraction of water molecles to some surfaces.
- in a plant, water moves up by adhesion up the xylem and through cellulose cell walls

Question 16

what is cohesion?

Answer 16

• it is the attraction of water molecules to other water molecules.
• water molecules are polar. polar molecules are attracted to toher polar molecules.

Question 17

what is transpiration?

Answer 17

as water is lost from the stomata, its loss creates a negative pressure at the top of the xylem vessel. this draws water up the xylem vessel.

Question 18

what is translocation?

Answer 18

transport of organic solutes (phloem sap) around the plant from the leaves.
- actively pumped into companion cells
- it moves into the phloem by active transport through membrane proteins or by simple diffusion through plasmodesmata.
- it moves down the phloem roots, under pressure created by osmosis
- roots, shoots and fruit actively remove the sucrose from the plant and so the pressure at these points is lower

Question 19

what do muscle tissues do?

Answer 19

allows contaction and movement

Question 20

what does a nervous tissue do?

Answer 20

detects stimuli and transmits electrical signals

Question 21

what does the epithelial tissue do?

Answer 21

covers the internal and external surfaces of the body
- They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.

Question 22

what does connective tissue do?

Answer 22

connects and supports other tissues and organs in the body

Question 23

what does the digestive system do?

Answer 23

the digestive system is responsible for breaking down and processing food for the body to use, as well as eliminating food waste that is not absorbed.

Question 24

what does the excretory system do?

Answer 24

the excretory system is responsible for removing waste substances from the blood via excretion and assisting in the control of waterbalance in the body
- removes urea from the body

Question 25

what does the endocrine system do?

Answer 25

the endocrine system is responsible for producing hormones that can be transported in the bloodstream to regulate distant organs/cells.

Question 26

what is an endocrine gland?

Answer 26

a gland which produces hormones.
they are ductless and secrete their hormones directly into the bloodstream.