Cells, tissues, organs and body systems

Question 1

define uni-cellular

Answer 1

single celled, the single cell is able to perform all life functions

Question 2

multicellular organisms have what 4/5 levels of organisations - ranging from simplest to most complex

Answer 2

1. cells
2. tissues
3. organs
4. organ systems

Question 3

describe cells

Answer 3

basic unit of structure in living things

may serve a specific function with the organism

e.g. blood cells, nerve cells

Question 4

describe tissues

Answer 4

made up of cells that are similar in structure and function and work together to perform a specific activity

e.g. blood, bone

Question 5

describe organs

Answer 5

made up of tissues that works together to perform a specific activity

e.g. heart, brain, skin

Question 6

describe organ systems

Answer 6

group of two of more tissues that work together to perform a specific function

e.g. circulatory system, nervous system

Question 7

how many organ systems are in the human body>

Answer 7

11

circulatory
digestive
edocrine
excretory
immune
integumentary
muscular
nervous
reproductive
respiratory
skeletal

Question 8

autotrophs

Answer 8

able to make their own energy-containing organic molecules from inorganic raw material by using energy sources such as light

e.g. plants

Question 9

heterotrophs

Answer 9

must use food that comes from other organisms in the form of fats, carbohydrates and proteins

Question 10

what are the two main stages within photosynthesis

Answer 10

Light dependent reactions:
- occur in the grana, and require the direct energy of light to make energy-carrier molecules that are used in the second process

Light independent reactions:
- occur in the stroma of the chloroplasts

Question 11

name 5 things in the structure of a leaf

Answer 11

• upper epidermis
• palisade mesophyll
• spongy mesophyll
• vascular tissue
• leaf shape

Question 12

describe the upper epidermis and its role

Answer 12

consists of a single layer of cells found on the upper surface of the leaf

covered by a thick waxy cuticle

main function is water conservation. It prevents the loss of water from the upper surface where the light intensity and heat are the greatest.

Question 13

describe the palisade mesophyll and its role

Answer 13

consists of tightly packed cylindrical cells.

contains many chloroplasts as it is the main photosynthetic tissue.

found on the upper half of the leaf (upper surface) where the light intensity is the greatest.

Question 14

describe the spongy mesophyll and its role

Answer 14

made up of loosely packed cells.

found in the lower half of the leaf (lower surface)

has few chloroplasts

provides gas exchange (CO2 uptake and O2release) and therefore needs to be close to the stomata found in the lower epidermis

Question 15

describe the vascular tissue and its role

Answer 15

Consists of xylem and phloem which are found in the veins of the leaf.

The veins in the leaf are positioned in the middle so that all the cells are in close contact with the vascular tissue.

The xylem consists of xylem vessels (dead structure) which are long and tubular and transports water into the leaf to replace the water that has been lost through transpiration.

The phloem is made up of living cells with pores in between them. It transports the products of photosynthesis out of the leaf.

Question 16

describe the leaf shape and its role

Answer 16

The orientation of a surface, such as a leaf, influences the energy balance of the surface.

The heat load of a leaf can be influenced by air movement and by evaporation (transpiration) of water from a leaf. This means the larger the leaf the more surface area available for light energy. This is beneficial for photosynthesis but needs to be balanced with water loss from transpiration.

Question 17

where does photosynthesis occur in plants

Answer 17

in the leaves

Question 18

what are the 2 main vascular tissues in plants

Answer 18

xylem

phloem

Question 19

explain role of the xylem and how it’s adapted

Answer 19

transports water and minerals

one way only (upwards)

no end walls between cells

thick walls stiffened with lignin

Question 20

how does transpiration enable upward water movement in a plant

Answer 20

• evaporation of water from leaf surfaces

- water is cohesive (cohesive forces between water molecules pulls them up to replace the evaporated water)

Question 21

explain role of the phloem and who it’s adapted

Answer 21

transports sugar molecules

cells have end walls with perforations

two-way flow (up and down)

materials able to move in the phloem as a result of active transport, osmosis and turgor pressure

Question 22

where are sugars produced in a plant

Answer 22

in the leaves

Question 23

describe what occurs in the phloem

Answer 23

1. sugars produced in leaves (sinks) as part of photosynthesis
2. these sugars are moves across to the phloem cells called sieve tub elements (via active transport)
3. because of high solute concentration water moves into these cells via osmosis
4. the inflow of water increases turgor pressure at the source, causing the movement of water and carbohydrates through the seven tube elements toward a sugar sink

Question 24

what is sap

Answer 24

a mixture of water and minerals that flow through the xylem

Question 25

how surface area of plants are maximised

Answer 25

• root hair cells
• root structure
• leaf shape/structure

Question 26

how can the rate of a reaction be increased

Answer 26

• by increasing the surface area of one of the reactants, e.g. by making it into a powder

Question 27

what happens if the surface area of a reactant is increased

Answer 27

More particles are exposed to the other reactant

There are more collisions

The rate of reaction increases

Question 28

name the main organs involved in digestion

Answer 28

mouth and associated accessory organs

pharynx and esophagus

stomach

small intestine (as well as liver, gallbladder and pancreas)

large intestine

Question 29

major functions of mouth and associated accessory organs

Answer 29

mechanical breakdown: mastication (chewing) by teach and mixing movements of tongue

digestion: salivary amylase in saliva (produced by salivary glands) begins chemical breakdown of starch

mucus in saliva helps dissolved foods = means that can be tasted + moistens food so tongue can compact it into a bolus

teeth break it up, increasing SA making it easier to swallow

Question 30

major functions of pharynx and esophagus

Answer 30

where the food bolus is pushed towards the stomach via peristalsis

Question 31

major functions of stomach

Answer 31

peristaltic waves mix food with gastric juice and propel it into duodenum

pepsin begins the digestion of proteins

absorbs a few fat-suluble

hydrochloric acid produced and activates protein-digesting enzymes

Question 32

major functions of small intestine (as well as liver, gallbladder and pancreas)

Answer 32

segmentation by smooth muscle of the small intestine continually mixes contents wit digestive juices, and along with short-distance peristaltic waves, moves food along tract, allowing sufficient time for digestion and absorption

digestive enzymes delivered from pancreas and brush border enzymes attached to microvilli

small intestine contains villi and microvilli to increase SA

gall bladder stores bile until ready for digestion

liver produces bile by liver emulsifies fats

Question 33

major functions of large intestine

Answer 33

absorbs most remaining water, electrolytes and vitamins produced by bacteria