Autotroph Structure and Function

Question 1

What is an autotroph?

Answer 1

An organism that produces its own nutrition through photosynthesis or chemosynthesis.

Question 2

What is a heterotroph?

Answer 2

An organism that cannot produce its own food and has to ingest all its nutrients.

Question 3

Distinguish between vascular and non-vascular plants.

Answer 3

Vascular plants have a transport system to move substances around its body. Non-vascular plants do not possess this transport system.

Question 4

What are the main functions of the root system?

Answer 4

Anchor the plant, absorb water an inorganic nutrients from soil.

Question 5

How is the root system specialised for its function?

Answer 5

Extensive branching increases SA and helps anchor plant.
Root hairs on epidermal cells protrude into the soil, increasing SA up to 12 times.
Water enters root across entire root system SA, across the flattened epidermal cells.

Question 6

Describe how substances are moved into and out of the roots.

Answer 6

Water moves into the roots via osmosis, while mineral ions follow by diffusion. If the concentration gradient is not high enough, active transport and facilitated diffusion may be used. Oxygen diffuses into the roots, and carbon dioxide diffuses out.

Question 7

What are the two main structures that make up the shoot system?

Answer 7

Stem and leaves

Question 8

What is the stem made of, and what are its functions?

Answer 8

The stem contains dermal tissue, vascular tissue and ground tissue. It provides structural support and a transport pathway between the stem and the leaves.

Question 9

What is the role of dermal tissue in the stem?

Answer 9

The dermal tissue makes up the outer layer of the stem and provides waterproofing, protection and control of gas exchange.

Question 10

What is the role of vascular tissue in the stem?

Answer 10

Xylem and phloem vessels are arranged in vascular bundles in the stem to transport substances from the roots to the leaves.

Question 11

What is the role of ground tissue in the stem?

Answer 11

Ground tissue in the stem fills in around the vascular tissue, providing storage and support.

Question 12

What are the main roles of the leaves?

Answer 12

Absorb sunlight and CO2 and produce glucose through photosynthesis. Leaves are also the sight of transpiration (water evaporates from leaf to help xylem)

Question 13

How is the structure of leaves suited to absorbing sunlight?

Answer 13

Leaves are thin and flat, which maximises the surface area for absorbing light energy. The thin structure also means that no internal cells are too far from the surface to absorb sunlight. The epidermis of the leaves is transparent to let light through.

Question 14

What is the mesophyll of the leaf?

Answer 14

The middle layers, composed of palisade cells and spongy cells.

Question 15

What is the structure and role of palisade cells?

Answer 15

Palisade cells are elongated, dense with chloroplasts, main photosynthetic cells. Situated vertically, exposed to maximum amount of sunlight.

Question 16

What is the structure and role of spongy mesophyll cells?

Answer 16

Second most important photosynthetic cells, situated between palisade cells and lower epidermis. Irregular shape and distribution.

Question 17

How are the leaves of rainforest plants adapted to absorbing sunlight?

Answer 17

Plants on the rainforest floor have large, flat leaves to maximise sunlight absorption, and a dark green, indicating high chloroplast concentration.

Question 18

How are the leaves of desert plants adapted to absorbing sunlight?

Answer 18

They have leaves that are very small, with minimal surface area, so they can absorb necessary sunlight, and reduce water loss.

Question 19

What is the role of the epidermal cells of the leaf?

Answer 19

They are simple, flattened cells that cover the leaf and protect its inner tissues. They secrete a waterproof cuticle to prevent water loss. These cells are transparent to allow sunlight through.

Question 20

Describe vascular tissue distribution in leaves.

Answer 20

vascular tissue supports the leaf blade, and passes through as ‘veins’ in the leaf. The main vein in the leaf is called the ‘midrib’. The distribution of vascular branches throughout leaves ensures no leaf cells are too far away from a source of transport.

Question 21

Describe how the process of cellular respiration in plants is ‘masked’ by photosynthesis.

Answer 21

Oxygen produced by photosynthesis is used by respiration. Excess released. Carbon dioxide produced by respiration is used in photosynthesis. The net gaseous exchange observed in plants during the day is associated with photosynthesis.